Influence of volume overload on endogenous erythropoietin production in hemodialysis patients

Influence of volume overload on endogenous erythropoietin production in hemodialysis patients | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Influence of volume overload on endogenous erythropoietin production in hemodialysis patients Shoichiro Daimon, Akihiko Koshino, Yasunori Iwata This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7985285/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Anemia in hemodialysis patients is primarily attributed to insufficient erythropoietin production. In patients with heart failure-related anemia, erythropoietin production is often inadequate relative to the hemoglobin level. Therefore, we hypothesized that cardiac stress induced by volume overload in hemodialysis patients might influence endogenous erythropoietin production and anemia status. Methods Changes in serum erythropoietin, hemoglobin, total protein, and reticulocyte levels across three consecutive hemodialysis sessions within one week were investigated. All patients were undergoing three times weekly hemodialysis and were not receiving erythropoiesis-stimulating agents or hypoxia-inducible factor prolyl hydroxylase inhibitors. Patients were divided into three groups based on the percentage of body weight gain at the first session of the week, relative to the weight at the end of the previous session (Group A: >5%, n = 11; Group B: 3 − 5%, n = 15; and Group C: <3%, n = 5). Results In Groups A and B, both total protein and hemoglobin levels at the beginning of the second and third sessions were significantly higher than those at the first session, which suggests hemoconcentration due to water removal. However, relative to the level at the beginning of the first session, the serum erythropoietin level at the beginning of the second and third sessions increased more drastically (Group A: 82.5 ± 130.3%, and 99.1 ± 118.8%; Group B: 79.6 ± 130.3%, and 83.0 ± 114.6%, respectively) than the total protein (Group A: 4.9 ± 2.6%, and 5.6 ± 2.9%; Group B: 2.6 ± 4.0%, and 2.5 ± 3.9%, respectively) and hemoglobin levels (Group A: 4.1 ± 3.7%, and 5.5 ± 2.1%; Group B: 3.4 ± 3.3%, and 3.2 ± 4.3%, respectively). Changes in these parameters in Group C were unremarkable, and changes in reticulocyte count were unremarkable across all groups. Conclusion The disproportionate increase in the serum erythropoietin level suggests a stimulation of innate erythropoietin production rather than mere hemoconcentration. Endogenous erythropoietin production is stimulated by the excessive water removal necessary to correct volume overload in hemodialysis patients. Further research is needed to elucidate the underlying mechanisms of this erythropoietin stimulation and its potential influence on hematopoiesis and the patient's anemia status. hemodialysis anemia erythropoietin volume overload Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Introduction In patients with non–dialysis-dependent (NDD) and dialysis-dependent (DD) chronic kidney disease (CKD), anemia is common [ 1 , 2 ]. Insufficient erythropoietin (EPO) production is considered the primary cause of this anemia [ 3 ], and the administration of erythropoiesis-stimulating agents (ESAs) has become the mainstay of anemia treatment in these populations [ 3 – 5 ]. Anemia is also common in patients with heart failure [ 6 ]. Not only oxygen deficiency but also intravascular volume and blood viscosity can influence endogenous EPO production [ 7 , 8 ], and anemia in patients with heart failure is often characterized by a disproportionately low serum EPO concentration for the degree of anemia [ 9 ]. Therefore, we hypothesized that endogenous EPO production and anemia status might be influenced by volume overload in CKD patients, especially in hemodialysis (HD) patients who suffer from volume overload due to oliguria or anuria. In this study, we investigated the changes in endogenous EPO production following water removal in HD patients who were not receiving ESAs or hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs). Methods This study included 31 patients undergoing maintenance HD three times weekly who were not receiving ESAs or HIF-PHIs. We investigated changes in serum EPO, hemoglobin (Hb), total protein (TP), and reticulocyte levels across three consecutive HD sessions within one week. As shown in Table 1, patients were divided into three groups based on the percentage of body weight gain at the first session of the week, relative to their dry weight at the end of the previous session (Group A: >5%, n = 11; Group B: 3 − 5%, n = 15; and Group C: <3%, n = 5). Statistics Data are expressed as mean ± standard deviation. A paired t-test was used to compare differences in quantitative variables within each group. Statistical significance was defined as a p -value of less than 0.05. Results The body weight gain at the first HD session of the study week was 3.76 ± 0.68 kg, 2.82 ± 0.87 kg, and 1.08 ± 0.39 kg for Group A, B, and C, respectively, corresponding to 6.10 ± 0.72%, 4.17 ± 0.43%, and 1.54 ± 0.73% of their body weight at the end of the last session of the previous week, respectively (Table 1). As shown in Figs. 1 and 2 , in Groups A and B, the body weight at the end of the first session of the week was significantly higher than that at the end of the last session of the previous week ( p < 0.005 and p < 0.05, respectively) because the body weight gain was too great to be fully removed during the first session. However, by the end of the third session, the body weight had returned to the baseline level. As shown in Figs. 3 and 4 , in Groups A and B, serum EPO, Hb, and TP levels were significantly higher at the beginning of the second and third sessions than at the first session, with the exception of the EPO level at the second session in Group A. The rates of increase in TP levels at the beginning of the second and third sessions compared to the first session were as follows: Group A, 4.9 ± 2.6% and 5.6 ± 2.9%; Group B, 2.6 ± 4.0% and 2.5 ± 3.9%, respectively. The corresponding rates of increase in Hb levels were: Group A, 4.1 ± 3.7% and 5.5 ± 2.1%; Group B, 3.4 ± 3.3% and 3.2 ± 4.3%, respectively. The serum EPO levels at the beginning of the second and third sessions increased more drastically (Group A, 82.5 ± 130.3% and 99.1 ± 118.8%; Group B, 79.6 ± 130.3% and 83.0 ± 114.6%, respectively) than the TP and Hb levels (Fig. 5 ). Changes in these parameters in Group C were not significant, and changes in the reticulocyte count were not significant across all groups. Discussion Although EPO production capacity and its regulation are not completely exhausted even in patients with end-stage NDD- or DD-CKD [ 10 – 12 ], decreased EPO production capacity is considered the primary cause of anemia. Other possible causes of renal anemia include suppression of erythropoiesis, hypoproliferative bone marrow function, shortened red blood cell lifespan, and disorders of iron metabolism; however, these factors are not yet fully understood [ 3 ]. EPO production is regulated by oxygen deficiency [ 13 ]. In patients not on dialysis, although EPO production increases progressively according to New York Heart Association (NYHA) classes II, III, and IV [ 14 ], this increase is likely attributable to oxygen deficiency. Even in HD patients, the serum EPO concentration increases exponentially in those with heart failure and very high brain natriuretic peptide levels (> 2000 pg/mL), suggesting that EPO production is stimulated by hypoxia [ 15 ]. This indicates that the endogenous EPO response to oxygen supply status persists in DD-CKD patients. In addition to patients with CKD, anemia is also common in those with heart failure [ 6 ]. Although structural renal disease, which can reduce EPO production, is infrequent, anemia in heart failure patients is characterized by a disproportionately low serum EPO concentration for the degree of anemia [ 9 ]. Endogenous EPO production is influenced not only by oxygen deficiency but also by changes in intravascular volume or blood viscosity [ 7 , 8 ]. EPO production is suppressed in milder forms of heart failure or mild volume overload without hypoxia [ 7 – 9 , 16 , 17 ]. In healthy subjects, EPO and copeptin (a surrogate measure of vasopressin) production change in response to central venous pressure; a reduction in central venous pressure leads to an increase in plasma EPO and copeptin concentrations. Thus, the production of EPO and vasopressin is regulated to control erythropoiesis and fluid volume, respectively, thereby maintaining homeostasis of blood volume and possibly Hb concentration. If the same regulation occurs in anuric HD patients with volume overload, it can be speculated that their EPO and vasopressin production is suppressed. While suppressed EPO production leads to suppressed erythropoiesis, the corresponding fluid regulation via vasopressin suppression is impaired in oliguric or anuric HD patients. Thus, volume overload may result in a decrease in Hb levels, which is not necessarily due to hemodilution but rather a decrease in red blood cells (true anemia). Although we have previously reported the possibility of volume overload as a cause of anemia in HD patients [ 18 , 19 ], to the best of our knowledge, changes in endogenous EPO production in response to volume overload in HD patients have not been previously reported. In the current study, we demonstrated that endogenous EPO production is stimulated by water removal in HD patients with volume overload. Conversely, volume overload may suppress EPO production in these patients. In Group C, the EPO level at the fourth session decreased significantly compared to that at the first session (Figs. 3 and 4 ), which may have been influenced by a greater body weight gain before the fourth session (2.10 ± 0.84 kg) compared to the first session (1.08 ± 0.39 kg), possibly due to higher fluid intake. An increase in serum EPO levels is expected to be followed by an increase in reticulocyte levels, and subsequently, an increase in Hb levels. As shown in Fig. 6 , in HD patients, reticulocyte levels increase promptly after ESA administration, in proportion to the ESA dose. ESA administration in HD patients induces a supraphysiological peak EPO concentration, which has been reported to be more than 100 times greater than the trough concentration [ 20 ], and can induce a rapid increase in reticulocyte levels. In contrast, in the current study, despite the increase in EPO levels in patients in Groups A and B, reticulocyte counts did not increase. Although the rate of increase in EPO levels was substantial, this increase was induced by excessive water removal and the resulting EPO levels remained within the physiological range. This may not have been sufficient to induce a significant and prompt increase in reticulocyte levels. However, this does not rule out the possibility that this increase in EPO could lead to a later improvement in anemia status. We often observe an inverse relationship between Hb levels and the cardio-thoracic ratio (Fig. 7 ), suggesting that sustained strict water removal can lead to anemia improvement. Figure 8 shows the changes in Hb levels, reticulocyte counts, mean corpuscular Hb levels, and trough EPO levels of five HD patients in our clinic who were switched from darbepoetin alfa to roxadustat. Serum EPO concentrations during roxadustat administration were equivalent to those of healthy subjects [ 21 ] and were much lower than the trough EPO concentrations observed during the administration of darbepoetin alfa. These findings suggest that the influence of serum EPO levels on erythropoiesis is fundamentally different depending on whether the EPO is exogenous (from ESA administration) or endogenous. A high serum endogenous EPO level is not necessarily required to maintain adequate erythropoiesis and Hb levels in HD patients. The possible mechanisms of anemia improvement by water removal in patients with volume overload may not be exclusively attributed to increased EPO production. It has been reported that iron deficiency in patients with mild-to-moderate heart failure is likely to be functional rather than absolute [ 22 ]. Thus, water removal in HD patients may improve their anemia status by improving functional iron deficiency. However, compared to the change in Hb levels following ESA administration, a longer period may be required to observe a change in Hb levels. It is conceivable that the relief of cardiac stress by water removal can improve the anemia status by increasing EPO production along with improving iron utilization. The question arises as to whether the reduction of EPO production in HD patients with volume overload is an adaptive mechanism or simply a harmful disorder that impairs Hb level maintenance. Hung et al. reported a negative correlation between the level of overhydration and Hb levels in NDD-CKD patients and hypothesized that “anemia in CKD is, at least in part, an adaptive response to the underlying state of fluid retention, cardiac dysfunction, and arteriosclerosis. Moderate anemia results in reduced blood viscosity and blood volume, which decreases left ventricular afterload and may improve microvascular perfusion in NDD-CKD patients” [ 23 ]. Thus, it is possible that the suppression of EPO production and adjustment to a lower Hb level is an “adaptive response” rather than a harmful disorder. Indeed, in patients with mild-to-moderate anemia due to systolic heart failure, ESA treatment resulted in more thromboembolic adverse events with equivalent clinical outcomes than placebo [ 24 ], and ESA administration is not recommended for these patients [ 25 ]. Similarly, if the main cause of anemia exacerbation in patients with NDD- and DD-CKD is volume overload, correcting the volume overload is more rational than initiating or increasing the dose of ESAs. The initiation or dose adjustment of ESAs should be considered only after correcting volume overload and ensuring sufficient iron supplementation. Conclusions Endogenous EPO production is stimulated by the removal of excess fluid in HD patients. Further research is needed to elucidate the underlying mechanisms of this EPO stimulation and its potential influence on hematopoiesis and the patient's anemia status. Abbreviations NDD non–dialysis-dependent DD dialysis-dependent CKD chronic kidney disease EPO erythropoietin ESA erythropoiesis-stimulating agent HD hemodialysis HIF-PHD hypoxia-inducible factor prolyl hydroxylase Declarations Acknowledgments The authors thank all the staff members working at Daimon Clinic for Internal Medicine, Nephrology and Dialysis. Funding This study was not supported by grants or funding. Author information Authors and Affiliations Shoichiro Daimon Department of Nephrology, Daimon Clinic for Internal Medicine, Nephrology and Dialysis, Nonoichi, Ishikawa, 921-8802, Japan Akihiko Koshino, Yasunori Iwata Department of Nephrology and Rheumatology, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, 920-0934, Japan Author contributions S.D. contributed to the writing of the manuscript. S.D., A.K. and Y.I. have read and approved the final manuscript. Corresponding author Correspondence to Shoichiro Daimon. Ethics approval and consent to participate All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee at the facility in which the studies were conducted and with the guidelines of the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. This study was approved by institutional ethical committee and informed consent for publication was obtained from the individual participants included in the study. Consent for publication Informed consent for publication was obtained from the individual participants included in the study. Availability of data and materials The datasets generated during the current study are available from the corresponding author upon reasonable request. Competing interests The authors declare no competing interests. References Goodkin DA, Fuller DS, Robinson BM, Combe C, Fluck R, Mendelssohn D, et al. Naturally occurring higher hemoglobin concentration does not increase mortality among patients on hemodialysis. J Am Soc Nephrol. 2011; 22:358–65. https://doi.org/10.1681/ASN . 20100 20173. Stauffer ME, Fan T. Prevalence of anemia in chronic kidney disease in the United States. PLoS One. 2014;9: e84943. https://doi.org/10.1371/journal . pone. 00849 43. Yamamoto H, Nishi S, Tomo T, Masakane I, Saito K, Nangaku M, et al. 2015 Japanese society for dialysis therapy: guidelines for renal anemia in chronic kidney disease. Renal Replace Therapy. 2017; 3:36. https://doi.org/10.1186/s41100-017-0114-y . Kidney Disease Improving Global Outcomes (KDIGO) (2012) Clinical practice guideline for anemia in chronic kidney disease. Kidney Int Suppl vol 2, pp 292–298. https://doi.org/10.1038/kisup . 2012. 34 Japanese Society of Nephrology. Essential points from evidence-based clinical practice guideline for chronic kidney disease 2023. Clin Exp Nephrol. 2024;28(6):473–95. https://doi.org/10.1007/s10157-024-02497-4 . Groenveld HF, Januzzi JL, Damman K, van Wijngaarden J, Hillege HL, van Veldhuisen DJ, et al. Anemia and mortality in heart failure patients a systematic review and meta-analysis. J Am Coll Cardiol. 2008; 52(10): 818–827. doi: 10.1016/j.jacc.2008.04.061 . Breymann C, Rohling R, Huch A, Huch R. Intraoperative endogenous erythropoietin levels and changes in intravascular blood volume in healthy humans. Ann Hematol. 2000; 79(4): 183–186. doi: 10.1007/s002770050577 . Kirsch KA, Schlemmer M, De Santo NG, Cirillo M, Perna A, Gunga HC. Erythropoietin as a volume-regulating hormone: an integrated view. Semin Nephrol. 2005; 25(6): 388–391. doi: 10.1016/j.semnephrol.2005.05.007 . Montero D, Haider T, Flammer AJ. Erythropoietin response to anaemia in heart failure. Eur J Prev Cardiol. 2019; 26(1): 7–17. doi: 10.1177/2047487318790823 . McGonigle RJ, Wallin JD, Shadduck RK, Fisher JW. Erythropoietin deficiency and inhibition of erythropoiesis in renal insufficiency. Kidney Int. 1984; 25(2): 437–444. doi: 10.1038/ki.1984.36 . Mercadal L, Metzger M, Casadevall N, Haymann JP, Karras A, Boffa JJ, et al for NephroTest Study Group. Timing and determinants of erythropoietin deficiency in chronic kidney disease. Clin J Am Soc Nephrol. 2012; 7(1): 35–42. doi: 10.2215/CJN.04690511 . Radtke HW, Claussner A, Erbes PM, Scheuermann EH, Schoeppe W, Koch KM. Serum erythropoietin concentration in chronic renal failure: relationship to degree of anemia and excretory renal function. Blood. 1979; 54(4): 877–884. Koury MJ, Haase VH. Anaemia in kidney disease: harnessing hypoxia responses for therapy. Nat Rev Nephrol. 2015; 11(7): 394–410. doi: 10.1038/nrneph.2015.82 . Volpe M, Tritto C, Testa U, Rao MA, Martucci R, Mirante A, et al. Blood levels of erythropoietin in congestive heart failure and correlation with clinical, hemodynamic, and hormonal profiles. Am J Cardiol. 1994; 74(5): 468–473. doi: 10.1016/0002-9149(94)90905-9 . Kumagai J, Yorioka N, Kawanishi H, Moriishi M, Komiya Y, Asakimori Y, et al. Relationship between erythropoietin and chronic heart failure in patients on chronic hemodialysis. J Am Soc Nephrol. 1999; 10(11): 2407–2411. doi: 10.1681/ASN.V10112407 . Anand IS, Gupta P. Anemia and Iron Deficiency in Heart Failure: Current Concepts and Emerging Therapies. Circulation. 2018; 138(1): 80–98. doi: 10.1161/CIRCULATIONAHA.118.030099 . Montero D, Rauber S, Goetze JP, Lundby C. Reduction in central venous pressure enhances erythropoietin synthesis: role of volume-regulating hormones. Acta Physiol (Oxf). 2016; 218(2): 89–97. doi: 10.1111/apha.12708 . Daimon S. Possible role of cardiovascular stress induced by the volume load as a cause of anemia in hemodialysis patients: a case of a maintenance hemodialysis patient with a literature review. Ren Replace Ther. 2024; 10:14. doi: 10.1186/s41100-024-00530-6 . Daimon S, Reconsideration of the anemia management strategy for chronic kidney disease and dialysis patients. Ren Replace Ther, 2025; 11: 16, doi: 10.1186/s41100-025-00612-z . Hara K, Takahashi N, Wakamatsu A, Caltabiano S. Pharmacokinetics, pharmacodynamics and safety of single, oral doses of GSK1278863, a novel HIF-prolyl hydroxylase inhibitor, in healthy Japanese and Caucasian subjects. Drug Metab Pharmacokinet. 2015; 30(6): 410–418. doi: 10.1016/j.dmpk.2015.08.004 . Grote Beverborg N, Verweij N, Klip IT, van der Wal HH, Voors AA, van Veldhuisen DJ, et al. Erythropoietin in the general population: reference ranges and clinical, biochemical and genetic correlates. PLoS One. 2015; 10(4): e0125215. doi: 10.1371/journal.pone.0125215 . Packer M. How can sodium-glucose cotransporter 2 inhibitors stimulate erythrocytosis in patients who are iron-deficient? Implications for understanding iron homeostasis in heart failure. Eur J Heart Fail. 2022; 24(12): 2287–2296. doi: 10.1002/ejhf.2731 . Hung SC, Kuo KL, Peng CH, Wu CH, Wang YC, Tarng DC. Association of fluid retention with anemia and clinical outcomes among patients with chronic kidney disease. J Am Heart Assoc. 2015; 4(1): e001480. doi: 10.1161/JAHA.114.001480 . Swedberg K, Young JB, Anand IS, Cheng S, Desai AS, Diaz R, et al for RED-HF Committees; RED-HF Investigators. Treatment of anemia with darbepoetin alfa in systolic heart failure. N Engl J Med. 2013; 368(13): 1210–1219. doi: 10.1056/NEJMoa1214865 . Heidenreich PA, Bozkurt B, Aguilar D, Allen LA, Byun JJ, Colvin MM, et al. 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2022; 145(18): e876-e894. doi: 10.1161/CIR.0000000000001062 . Table 1 Table 1 is available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files WCNTable.xlsx Table 1 Characteristics of patients BW, body weight; HD, hemodialysis; BUN, blood urea nitrogen; TSAT, transferrin saturation; CRP, C-reactive protein. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7985285","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":544525048,"identity":"c088160d-f04f-4c05-ac03-bb5185aab11a","order_by":0,"name":"Shoichiro Daimon","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA+ElEQVRIiWNgGAWjYDCCA4zNDAwGIBYPA8MHIMXGTooWxhkgLcwEtTDAlPAwMPOAaEJa+I4fbjb4ULBNnp//7MHHNr+2yfMxMzB++JiDW4vkmcTmxBkGtw1nzshLNs7tu23YxszALDlzG24tBgcSmw/zGNxm3HCDx0w6t+c2I1ALGzMvPi3nHzYf/mNw237/+TNm0pY9t+0Ja7mR2JzMYHA7cQNDjpk0w4/biQS1SN542GzYY3A7ecaNHGPD3obbyW3MjM14/cJ3Pv2xxI8/t237+88YPgAx5rc3H/zwEY8WVMDYBiYbiFUPAn9IUTwKRsEoGAUjBQAAxpJVucMyEzAAAAAASUVORK5CYII=","orcid":"","institution":"Daimon Clinic for Internal Medicine, Nephrology and Dialysis","correspondingAuthor":true,"prefix":"","firstName":"Shoichiro","middleName":"","lastName":"Daimon","suffix":""},{"id":544525049,"identity":"9c4d0faa-5ac1-42ca-8ebf-d4f7dfc3e6da","order_by":1,"name":"Akihiko Koshino","email":"","orcid":"","institution":"Graduate School of Medical Sciences, Kanazawa University","correspondingAuthor":false,"prefix":"","firstName":"Akihiko","middleName":"","lastName":"Koshino","suffix":""},{"id":544525050,"identity":"9358b7d3-bad5-4200-9299-60befc07228f","order_by":2,"name":"Yasunori Iwata","email":"","orcid":"","institution":"Graduate School of Medical Sciences, Kanazawa University","correspondingAuthor":false,"prefix":"","firstName":"Yasunori","middleName":"","lastName":"Iwata","suffix":""}],"badges":[],"createdAt":"2025-10-30 05:38:18","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7985285/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7985285/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":96367528,"identity":"3d81f783-2048-4c70-930f-244ddbe4bdf5","added_by":"auto","created_at":"2025-11-20 10:13:05","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":36230,"visible":true,"origin":"","legend":"","description":"","filename":"WCN2026manuscript.docx","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/8cc304de68f2c9d9a2c56e18.docx"},{"id":96366811,"identity":"9d0780a6-c0c7-4d34-823e-9601d6feaad4","added_by":"auto","created_at":"2025-11-20 10:11:55","extension":"xlsx","order_by":3,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":11527,"visible":true,"origin":"","legend":"","description":"","filename":"WCNTable.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/28c74f63fc63c08eb5fb62bb.xlsx"},{"id":96367316,"identity":"798f9afd-8b2f-43f0-ba3d-c7a60e86c213","added_by":"auto","created_at":"2025-11-20 10:12:31","extension":"json","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":5801,"visible":true,"origin":"","legend":"","description":"","filename":"e5c767e24a1b4d7c90817612b7c7cf76.json","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/042fcc12c44114296fbab9b1.json"},{"id":96355562,"identity":"f395a0e9-6f5d-4145-b31d-e1a3e8a1c93e","added_by":"auto","created_at":"2025-11-20 08:17:09","extension":"xml","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":67967,"visible":true,"origin":"","legend":"","description":"","filename":"e5c767e24a1b4d7c90817612b7c7cf761enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/ae8319cbc5e372ff6ce2ecd2.xml"},{"id":96355567,"identity":"343cf81f-defd-4d6d-96ce-3047cdd3836d","added_by":"auto","created_at":"2025-11-20 08:17:09","extension":"pptx","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":641722,"visible":true,"origin":"","legend":"","description":"","filename":"WCNRRTFig.1.pptx","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/519dac74d79efb276b44f204.pptx"},{"id":96366764,"identity":"b52f6646-ab57-4c76-b4be-74973fc3cd76","added_by":"auto","created_at":"2025-11-20 10:11:52","extension":"pptx","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":641361,"visible":true,"origin":"","legend":"","description":"","filename":"WCNRRTFig.2.pptx","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/6ee46ddb55a61768bf8c7de1.pptx"},{"id":96355574,"identity":"8b3faf87-e640-4641-a83e-e839d536a674","added_by":"auto","created_at":"2025-11-20 08:17:10","extension":"pptx","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":2381633,"visible":true,"origin":"","legend":"","description":"","filename":"WCNRRTFig.3.pptx","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/7f288a3adf40beba01962e63.pptx"},{"id":96355571,"identity":"d3cfcadc-6474-4911-a016-e494f673c733","added_by":"auto","created_at":"2025-11-20 08:17:09","extension":"pptx","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":2381201,"visible":true,"origin":"","legend":"","description":"","filename":"WCNRRTFig.4.pptx","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/b399e5c8571c07328ee49d55.pptx"},{"id":96355566,"identity":"aa2555ff-331e-40c6-a41a-91c73812fa72","added_by":"auto","created_at":"2025-11-20 08:17:09","extension":"pptx","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":63520,"visible":true,"origin":"","legend":"","description":"","filename":"WCNRRTFig.5.pptx","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/95f5e1a4f24e9732dff6a1ed.pptx"},{"id":96367561,"identity":"5edadd63-b365-4f6e-b41a-677872a74e4d","added_by":"auto","created_at":"2025-11-20 10:13:14","extension":"pptx","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":482429,"visible":true,"origin":"","legend":"","description":"","filename":"WCNRRTFig.6.pptx","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/8bc1ba7f3ebd2e1b142b51b7.pptx"},{"id":96355564,"identity":"aee40805-d231-4751-bcc3-b61cc4810cc9","added_by":"auto","created_at":"2025-11-20 08:17:09","extension":"pptx","order_by":18,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":47748,"visible":true,"origin":"","legend":"","description":"","filename":"WCNRRTFig.7.pptx","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/577f987fa2bfef70a190569c.pptx"},{"id":96355572,"identity":"326cad4a-10e7-4210-8cee-32f8a4ae9e66","added_by":"auto","created_at":"2025-11-20 08:17:09","extension":"pptx","order_by":19,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":240347,"visible":true,"origin":"","legend":"","description":"","filename":"WCNRRTFig.8.pptx","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/649c4d816d5b7d2ef9f072b3.pptx"},{"id":96366850,"identity":"818dd7aa-c926-4b64-82ee-94ff623bfefd","added_by":"auto","created_at":"2025-11-20 10:11:57","extension":"xml","order_by":20,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":66171,"visible":true,"origin":"","legend":"","description":"","filename":"e5c767e24a1b4d7c90817612b7c7cf761structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/4a7bb78ba740604b8c4fea71.xml"},{"id":96355568,"identity":"adacaf53-2e02-49f1-8cc9-7335403220e7","added_by":"auto","created_at":"2025-11-20 08:17:09","extension":"html","order_by":21,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":75068,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/f3834a5717022c62aa261e65.html"},{"id":96355553,"identity":"33327869-66c7-435e-8ac1-362dd3a3f617","added_by":"auto","created_at":"2025-11-20 08:17:09","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":40431,"visible":true,"origin":"","legend":"\u003cp\u003eChanges in body weight according to body weight gain at the first session of the study week.\u003c/p\u003e\n\u003cp\u003eHD, hemodialysis; hr, hour.\u003c/p\u003e","description":"","filename":"WCNRRTFig.11.png","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/1908e45d754f217fba9a926f.png"},{"id":96355556,"identity":"efd46d3e-eb1b-4bed-a62f-bf6118a3690d","added_by":"auto","created_at":"2025-11-20 08:17:09","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":46369,"visible":true,"origin":"","legend":"\u003cp\u003eBody weight differences to dry weight according to body weight gain at the first session of the study week.\u003c/p\u003e\n\u003cp\u003eHD, hemodialysis; hr, hour.\u003c/p\u003e","description":"","filename":"WCNRRTFig.21.png","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/fef4d773eefa6083187ebde7.png"},{"id":96355552,"identity":"e051d41e-f2c0-4a14-bac5-f22679e898d3","added_by":"auto","created_at":"2025-11-20 08:17:09","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":35658,"visible":true,"origin":"","legend":"\u003cp\u003eChanges in hemoglobin, total protein, erythropoietin and reticulocyte levels based on body weight gain.\u003c/p\u003e\n\u003cp\u003eHD, hemodialysis; hr, hour.\u003c/p\u003e","description":"","filename":"WCNRRTFig.31.png","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/32c69c2e4e25fd43ebeb511d.png"},{"id":96367472,"identity":"bc858da9-6508-492b-bb92-727256b8c285","added_by":"auto","created_at":"2025-11-20 10:12:52","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":32878,"visible":true,"origin":"","legend":"\u003cp\u003eChanges in Δhemoglobin, total protein, erythropoietin and reticulocyte levels based on body weight gain.\u003c/p\u003e\n\u003cp\u003eHD, hemodialysis; hr, hour.\u003c/p\u003e","description":"","filename":"WCNRRTFig.41.png","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/be3cb699497a23d99e7917c8.png"},{"id":96367508,"identity":"cba71932-4345-4dc3-ac20-1a382ef31f6a","added_by":"auto","created_at":"2025-11-20 10:12:56","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":51982,"visible":true,"origin":"","legend":"\u003cp\u003eRate of changes in hemoglobin, total protein and erythropoietin levels based on body weight gain.\u003c/p\u003e\n\u003cp\u003eHD, hemodialysis; hr, hour.\u003c/p\u003e","description":"","filename":"WCNRRTFig.51.png","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/a6e7dd871b35dcc0f381dc21.png"},{"id":96355557,"identity":"3b939719-5b2b-4a8a-b207-8c3271123695","added_by":"auto","created_at":"2025-11-20 08:17:09","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":38977,"visible":true,"origin":"","legend":"\u003cp\u003eChanges in the Δreticulocyte ratio (ref.: Day 0) after the injection of erythropoietin-stimulating agent.\u003c/p\u003e\n\u003cp\u003eCERA, continuous erythropoietin receptor activator; DA, darbepoetin alfa.\u003c/p\u003e\n\u003cp\u003eRepresented from Fig. 3 in ref. [19] under the permission.\u003c/p\u003e","description":"","filename":"WCNRRTFig.61.png","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/5c61cb9bd4e734c918bc18cf.png"},{"id":96367344,"identity":"dd22e1a5-3774-4c80-b2eb-f9cc52e8f6b2","added_by":"auto","created_at":"2025-11-20 10:12:36","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":27473,"visible":true,"origin":"","legend":"\u003cp\u003eChanges in the hemoglobin, cardiothoracic ratio, serum albumin, C-reactive protein, ferritin and transferrin saturation levels of a 48-year-old male hemodialysis patient.\u003c/p\u003e\n\u003cp\u003eCRP, C-reactive protein; TSAT, transferrin saturation.\u003c/p\u003e\n\u003cp\u003eModified from Fig. 11 in ref. [19] under the permission.\u003c/p\u003e","description":"","filename":"WCNRRTFig.71.png","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/69fb49d67f5cbba9f3f6c571.png"},{"id":96366593,"identity":"291afad3-5f87-4494-96d5-ce59ec17da45","added_by":"auto","created_at":"2025-11-20 10:11:36","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":29677,"visible":true,"origin":"","legend":"\u003cp\u003eChanges in hemoglobin levels, reticulocyte counts, and mean corpuscular hemoglobin and trough erythropoietin levels in hemodialysis patients (N=5).\u003c/p\u003e\n\u003cp\u003eRepresented from Fig. 12 in ref. [19] under the permission.\u003c/p\u003e","description":"","filename":"WCNRRTFig.81.png","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/f43a19dcc6804402db222220.png"},{"id":105970008,"identity":"aa6dd342-2279-4286-b1dd-218665b80774","added_by":"auto","created_at":"2026-04-02 03:11:12","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":697573,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/9e975c3a-37ff-4935-98c3-923ac3cf0ab8.pdf"},{"id":96355559,"identity":"df117a1b-1c51-4b35-9dc4-3f2bd0706c78","added_by":"auto","created_at":"2025-11-20 08:17:09","extension":"xlsx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":11527,"visible":true,"origin":"","legend":"\u003cp\u003eTable 1\u003c/p\u003e\n\u003cp\u003eCharacteristics of patients\u003c/p\u003e\n\u003cp\u003eBW, body weight; HD, hemodialysis; BUN, blood urea nitrogen; TSAT, transferrin saturation; CRP, C-reactive protein.\u003c/p\u003e","description":"","filename":"WCNTable.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-7985285/v1/a49f68f4b9d450900bd859cc.xlsx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Influence of volume overload on endogenous erythropoietin production in hemodialysis patients","fulltext":[{"header":"Introduction","content":"\u003cp\u003eIn patients with non\u0026ndash;dialysis-dependent (NDD) and dialysis-dependent (DD) chronic kidney disease (CKD), anemia is common [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Insufficient erythropoietin (EPO) production is considered the primary cause of this anemia [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], and the administration of erythropoiesis-stimulating agents (ESAs) has become the mainstay of anemia treatment in these populations [\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Anemia is also common in patients with heart failure [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Not only oxygen deficiency but also intravascular volume and blood viscosity can influence endogenous EPO production [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], and anemia in patients with heart failure is often characterized by a disproportionately low serum EPO concentration for the degree of anemia [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eTherefore, we hypothesized that endogenous EPO production and anemia status might be influenced by volume overload in CKD patients, especially in hemodialysis (HD) patients who suffer from volume overload due to oliguria or anuria. In this study, we investigated the changes in endogenous EPO production following water removal in HD patients who were not receiving ESAs or hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs).\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003eThis study included 31 patients undergoing maintenance HD three times weekly who were not receiving ESAs or HIF-PHIs. We investigated changes in serum EPO, hemoglobin (Hb), total protein (TP), and reticulocyte levels across three consecutive HD sessions within one week. As shown in Table\u0026nbsp;1, patients were divided into three groups based on the percentage of body weight gain at the first session of the week, relative to their dry weight at the end of the previous session (Group A: \u0026gt;5%, n\u0026thinsp;=\u0026thinsp;11; Group B: 3\u0026thinsp;\u0026minus;\u0026thinsp;5%, n\u0026thinsp;=\u0026thinsp;15; and Group C: \u0026lt;3%, n\u0026thinsp;=\u0026thinsp;5).\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStatistics\u003c/h2\u003e\u003cp\u003eData are expressed as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation. A paired t-test was used to compare differences in quantitative variables within each group. Statistical significance was defined as a \u003cem\u003ep\u003c/em\u003e-value of less than 0.05.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eThe body weight gain at the first HD session of the study week was 3.76\u0026thinsp;\u0026plusmn;\u0026thinsp;0.68 kg, 2.82\u0026thinsp;\u0026plusmn;\u0026thinsp;0.87 kg, and 1.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.39 kg for Group A, B, and C, respectively, corresponding to 6.10\u0026thinsp;\u0026plusmn;\u0026thinsp;0.72%, 4.17\u0026thinsp;\u0026plusmn;\u0026thinsp;0.43%, and 1.54\u0026thinsp;\u0026plusmn;\u0026thinsp;0.73% of their body weight at the end of the last session of the previous week, respectively (Table\u0026nbsp;1). As shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, in Groups A and B, the body weight at the end of the first session of the week was significantly higher than that at the end of the last session of the previous week (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.005 and \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05, respectively) because the body weight gain was too great to be fully removed during the first session. However, by the end of the third session, the body weight had returned to the baseline level.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eAs shown in Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e and \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, in Groups A and B, serum EPO, Hb, and TP levels were significantly higher at the beginning of the second and third sessions than at the first session, with the exception of the EPO level at the second session in Group A. The rates of increase in TP levels at the beginning of the second and third sessions compared to the first session were as follows: Group A, 4.9\u0026thinsp;\u0026plusmn;\u0026thinsp;2.6% and 5.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.9%; Group B, 2.6\u0026thinsp;\u0026plusmn;\u0026thinsp;4.0% and 2.5\u0026thinsp;\u0026plusmn;\u0026thinsp;3.9%, respectively. The corresponding rates of increase in Hb levels were: Group A, 4.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7% and 5.5\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1%; Group B, 3.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3% and 3.2\u0026thinsp;\u0026plusmn;\u0026thinsp;4.3%, respectively. The serum EPO levels at the beginning of the second and third sessions increased more drastically (Group A, 82.5\u0026thinsp;\u0026plusmn;\u0026thinsp;130.3% and 99.1\u0026thinsp;\u0026plusmn;\u0026thinsp;118.8%; Group B, 79.6\u0026thinsp;\u0026plusmn;\u0026thinsp;130.3% and 83.0\u0026thinsp;\u0026plusmn;\u0026thinsp;114.6%, respectively) than the TP and Hb levels (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). Changes in these parameters in Group C were not significant, and changes in the reticulocyte count were not significant across all groups.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eAlthough EPO production capacity and its regulation are not completely exhausted even in patients with end-stage NDD- or DD-CKD [\u003cspan additionalcitationids=\"CR11\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], decreased EPO production capacity is considered the primary cause of anemia. Other possible causes of renal anemia include suppression of erythropoiesis, hypoproliferative bone marrow function, shortened red blood cell lifespan, and disorders of iron metabolism; however, these factors are not yet fully understood [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eEPO production is regulated by oxygen deficiency [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. In patients not on dialysis, although EPO production increases progressively according to New York Heart Association (NYHA) classes II, III, and IV [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], this increase is likely attributable to oxygen deficiency. Even in HD patients, the serum EPO concentration increases exponentially in those with heart failure and very high brain natriuretic peptide levels (\u0026gt;\u0026thinsp;2000 pg/mL), suggesting that EPO production is stimulated by hypoxia [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. This indicates that the endogenous EPO response to oxygen supply status persists in DD-CKD patients.\u003c/p\u003e\u003cp\u003eIn addition to patients with CKD, anemia is also common in those with heart failure [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Although structural renal disease, which can reduce EPO production, is infrequent, anemia in heart failure patients is characterized by a disproportionately low serum EPO concentration for the degree of anemia [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Endogenous EPO production is influenced not only by oxygen deficiency but also by changes in intravascular volume or blood viscosity [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. EPO production is suppressed in milder forms of heart failure or mild volume overload without hypoxia [\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. In healthy subjects, EPO and copeptin (a surrogate measure of vasopressin) production change in response to central venous pressure; a reduction in central venous pressure leads to an increase in plasma EPO and copeptin concentrations. Thus, the production of EPO and vasopressin is regulated to control erythropoiesis and fluid volume, respectively, thereby maintaining homeostasis of blood volume and possibly Hb concentration. If the same regulation occurs in anuric HD patients with volume overload, it can be speculated that their EPO and vasopressin production is suppressed. While suppressed EPO production leads to suppressed erythropoiesis, the corresponding fluid regulation via vasopressin suppression is impaired in oliguric or anuric HD patients. Thus, volume overload may result in a decrease in Hb levels, which is not necessarily due to hemodilution but rather a decrease in red blood cells (true anemia). Although we have previously reported the possibility of volume overload as a cause of anemia in HD patients [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], to the best of our knowledge, changes in endogenous EPO production in response to volume overload in HD patients have not been previously reported. In the current study, we demonstrated that endogenous EPO production is stimulated by water removal in HD patients with volume overload. Conversely, volume overload may suppress EPO production in these patients. In Group C, the EPO level at the fourth session decreased significantly compared to that at the first session (Figs.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e and \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e), which may have been influenced by a greater body weight gain before the fourth session (2.10\u0026thinsp;\u0026plusmn;\u0026thinsp;0.84 kg) compared to the first session (1.08\u0026thinsp;\u0026plusmn;\u0026thinsp;0.39 kg), possibly due to higher fluid intake.\u003c/p\u003e\u003cp\u003eAn increase in serum EPO levels is expected to be followed by an increase in reticulocyte levels, and subsequently, an increase in Hb levels. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, in HD patients, reticulocyte levels increase promptly after ESA administration, in proportion to the ESA dose. ESA administration in HD patients induces a supraphysiological peak EPO concentration, which has been reported to be more than 100 times greater than the trough concentration [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e], and can induce a rapid increase in reticulocyte levels. In contrast, in the current study, despite the increase in EPO levels in patients in Groups A and B, reticulocyte counts did not increase. Although the rate of increase in EPO levels was substantial, this increase was induced by excessive water removal and the resulting EPO levels remained within the physiological range. This may not have been sufficient to induce a significant and prompt increase in reticulocyte levels. However, this does not rule out the possibility that this increase in EPO could lead to a later improvement in anemia status. We often observe an inverse relationship between Hb levels and the cardio-thoracic ratio (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e), suggesting that sustained strict water removal can lead to anemia improvement. Figure\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e shows the changes in Hb levels, reticulocyte counts, mean corpuscular Hb levels, and trough EPO levels of five HD patients in our clinic who were switched from darbepoetin alfa to roxadustat. Serum EPO concentrations during roxadustat administration were equivalent to those of healthy subjects [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] and were much lower than the trough EPO concentrations observed during the administration of darbepoetin alfa. These findings suggest that the influence of serum EPO levels on erythropoiesis is fundamentally different depending on whether the EPO is exogenous (from ESA administration) or endogenous. A high serum endogenous EPO level is not necessarily required to maintain adequate erythropoiesis and Hb levels in HD patients.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThe possible mechanisms of anemia improvement by water removal in patients with volume overload may not be exclusively attributed to increased EPO production. It has been reported that iron deficiency in patients with mild-to-moderate heart failure is likely to be functional rather than absolute [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Thus, water removal in HD patients may improve their anemia status by improving functional iron deficiency. However, compared to the change in Hb levels following ESA administration, a longer period may be required to observe a change in Hb levels. It is conceivable that the relief of cardiac stress by water removal can improve the anemia status by increasing EPO production along with improving iron utilization.\u003c/p\u003e\u003cp\u003eThe question arises as to whether the reduction of EPO production in HD patients with volume overload is an adaptive mechanism or simply a harmful disorder that impairs Hb level maintenance. Hung et al. reported a negative correlation between the level of overhydration and Hb levels in NDD-CKD patients and hypothesized that \u0026ldquo;anemia in CKD is, at least in part, an adaptive response to the underlying state of fluid retention, cardiac dysfunction, and arteriosclerosis. Moderate anemia results in reduced blood viscosity and blood volume, which decreases left ventricular afterload and may improve microvascular perfusion in NDD-CKD patients\u0026rdquo; [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Thus, it is possible that the suppression of EPO production and adjustment to a lower Hb level is an \u0026ldquo;adaptive response\u0026rdquo; rather than a harmful disorder. Indeed, in patients with mild-to-moderate anemia due to systolic heart failure, ESA treatment resulted in more thromboembolic adverse events with equivalent clinical outcomes than placebo [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e], and ESA administration is not recommended for these patients [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Similarly, if the main cause of anemia exacerbation in patients with NDD- and DD-CKD is volume overload, correcting the volume overload is more rational than initiating or increasing the dose of ESAs. The initiation or dose adjustment of ESAs should be considered only after correcting volume overload and ensuring sufficient iron supplementation.\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eEndogenous EPO production is stimulated by the removal of excess fluid in HD patients. Further research is needed to elucidate the underlying mechanisms of this EPO stimulation and its potential influence on hematopoiesis and the patient's anemia status.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eNDD\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003enon\u0026ndash;dialysis-dependent\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eDD\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003edialysis-dependent\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCKD\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003echronic kidney disease\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eEPO\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eerythropoietin\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eESA\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eerythropoiesis-stimulating agent\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eHD\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003ehemodialysis\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eHIF-PHD\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003ehypoxia-inducible factor prolyl hydroxylase\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors thank all the staff members working at Daimon Clinic for Internal\u003c/p\u003e\n\u003cp\u003eMedicine, Nephrology and Dialysis.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was not supported by grants or funding.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAuthors and Affiliations\u003c/p\u003e\n\u003cp\u003eShoichiro Daimon\u003c/p\u003e\n\u003cp\u003eDepartment of Nephrology, Daimon Clinic for Internal Medicine, Nephrology and Dialysis, Nonoichi, Ishikawa, 921-8802, Japan\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAkihiko Koshino, Yasunori Iwata\u003c/p\u003e\n\u003cp\u003eDepartment of Nephrology and Rheumatology, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, 920-0934, Japan\u003c/p\u003e\n\u003cp\u003eAuthor contributions\u003c/p\u003e\n\u003cp\u003eS.D. contributed to the writing of the manuscript. S.D., A.K. and Y.I. have read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003eCorresponding author\u003c/p\u003e\n\u003cp\u003eCorrespondence to Shoichiro Daimon.\u003c/p\u003e\n\u003cp\u003eEthics approval and consent to participate\u003c/p\u003e\n\u003cp\u003eAll procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee at the facility in which the studies were conducted and with the guidelines of the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.\u003c/p\u003e\n\u003cp\u003eThis study was approved by institutional ethical committee and informed consent for publication was obtained from the individual participants included in the study.\u003c/p\u003e\n\u003cp\u003eConsent for publication\u003c/p\u003e\n\u003cp\u003eInformed consent for publication was obtained from the individual participants included in the study.\u003c/p\u003e\n\u003cp\u003eAvailability of data and materials\u003c/p\u003e\n\u003cp\u003eThe datasets generated during the current study are available from the corresponding author upon reasonable request.\u003c/p\u003e\n\u003cp\u003eCompeting interests\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eGoodkin DA, Fuller DS, Robinson BM, Combe C, Fluck R, Mendelssohn D, et al. Naturally occurring higher hemoglobin concentration does not increase mortality among patients on hemodialysis. J Am Soc Nephrol. 2011; 22:358\u0026ndash;65. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1681/ASN\u003c/span\u003e\u003cspan address=\"10.1681/ASN\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. 20100 20173.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eStauffer ME, Fan T. Prevalence of anemia in chronic kidney disease in the United States. PLoS One. 2014;9: e84943. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1371/journal\u003c/span\u003e\u003cspan address=\"10.1371/journal\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. pone. 00849 43.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eYamamoto H, Nishi S, Tomo T, Masakane I, Saito K, Nangaku M, et al. 2015 Japanese society for dialysis therapy: guidelines for renal anemia in chronic kidney disease. Renal Replace Therapy. 2017; 3:36. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1186/s41100-017-0114-y\u003c/span\u003e\u003cspan address=\"10.1186/s41100-017-0114-y\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKidney Disease Improving Global Outcomes (KDIGO) (2012) Clinical practice guideline for anemia in chronic kidney disease. Kidney Int Suppl vol 2, pp 292\u0026ndash;298. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/kisup\u003c/span\u003e\u003cspan address=\"10.1038/kisup\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. 2012. 34\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJapanese Society of Nephrology. Essential points from evidence-based clinical practice guideline for chronic kidney disease 2023. Clin Exp Nephrol. 2024;28(6):473\u0026ndash;95. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10157-024-02497-4\u003c/span\u003e\u003cspan address=\"10.1007/s10157-024-02497-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGroenveld HF, Januzzi JL, Damman K, van Wijngaarden J, Hillege HL, van Veldhuisen DJ, et al. Anemia and mortality in heart failure patients a systematic review and meta-analysis. J Am Coll Cardiol. 2008; 52(10): 818\u0026ndash;827. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jacc.2008.04.061\u003c/span\u003e\u003cspan address=\"10.1016/j.jacc.2008.04.061\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eBreymann C, Rohling R, Huch A, Huch R. Intraoperative endogenous erythropoietin levels and changes in intravascular blood volume in healthy humans. Ann Hematol. 2000; 79(4): 183\u0026ndash;186. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s002770050577\u003c/span\u003e\u003cspan address=\"10.1007/s002770050577\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKirsch KA, Schlemmer M, De Santo NG, Cirillo M, Perna A, Gunga HC. Erythropoietin as a volume-regulating hormone: an integrated view. Semin Nephrol. 2005; 25(6): 388\u0026ndash;391. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.semnephrol.2005.05.007\u003c/span\u003e\u003cspan address=\"10.1016/j.semnephrol.2005.05.007\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMontero D, Haider T, Flammer AJ. Erythropoietin response to anaemia in heart failure. Eur J Prev Cardiol. 2019; 26(1): 7\u0026ndash;17. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1177/2047487318790823\u003c/span\u003e\u003cspan address=\"10.1177/2047487318790823\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMcGonigle RJ, Wallin JD, Shadduck RK, Fisher JW. Erythropoietin deficiency and inhibition of erythropoiesis in renal insufficiency. Kidney Int. 1984; 25(2): 437\u0026ndash;444. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/ki.1984.36\u003c/span\u003e\u003cspan address=\"10.1038/ki.1984.36\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMercadal L, Metzger M, Casadevall N, Haymann JP, Karras A, Boffa JJ, et al for NephroTest Study Group. Timing and determinants of erythropoietin deficiency in chronic kidney disease. Clin J Am Soc Nephrol. 2012; 7(1): 35\u0026ndash;42. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.2215/CJN.04690511\u003c/span\u003e\u003cspan address=\"10.2215/CJN.04690511\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRadtke HW, Claussner A, Erbes PM, Scheuermann EH, Schoeppe W, Koch KM. Serum erythropoietin concentration in chronic renal failure: relationship to degree of anemia and excretory renal function. Blood. 1979; 54(4): 877\u0026ndash;884.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKoury MJ, Haase VH. Anaemia in kidney disease: harnessing hypoxia responses for therapy. Nat Rev Nephrol. 2015; 11(7): 394\u0026ndash;410. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/nrneph.2015.82\u003c/span\u003e\u003cspan address=\"10.1038/nrneph.2015.82\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eVolpe M, Tritto C, Testa U, Rao MA, Martucci R, Mirante A, et al. Blood levels of erythropoietin in congestive heart failure and correlation with clinical, hemodynamic, and hormonal profiles. Am J Cardiol. 1994; 74(5): 468\u0026ndash;473. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/0002-9149(94)90905-9\u003c/span\u003e\u003cspan address=\"10.1016/0002-9149(94)90905-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eKumagai J, Yorioka N, Kawanishi H, Moriishi M, Komiya Y, Asakimori Y, et al. Relationship between erythropoietin and chronic heart failure in patients on chronic hemodialysis. J Am Soc Nephrol. 1999; 10(11): 2407\u0026ndash;2411. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1681/ASN.V10112407\u003c/span\u003e\u003cspan address=\"10.1681/ASN.V10112407\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAnand IS, Gupta P. Anemia and Iron Deficiency in Heart Failure: Current Concepts and Emerging Therapies. Circulation. 2018; 138(1): 80\u0026ndash;98. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1161/CIRCULATIONAHA.118.030099\u003c/span\u003e\u003cspan address=\"10.1161/CIRCULATIONAHA.118.030099\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMontero D, Rauber S, Goetze JP, Lundby C. Reduction in central venous pressure enhances erythropoietin synthesis: role of volume-regulating hormones. Acta Physiol (Oxf). 2016; 218(2): 89\u0026ndash;97. doi:\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1111/apha.12708\u003c/span\u003e\u003cspan address=\"10.1111/apha.12708\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDaimon S. Possible role of cardiovascular stress induced by the volume load as a cause of anemia in hemodialysis patients: a case of a maintenance hemodialysis patient with a literature review. Ren Replace Ther. 2024; 10:14. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s41100-024-00530-6\u003c/span\u003e\u003cspan address=\"10.1186/s41100-024-00530-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDaimon S, Reconsideration of the anemia management strategy for chronic kidney disease and dialysis patients. Ren Replace Ther, 2025; 11: 16, doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s41100-025-00612-z\u003c/span\u003e\u003cspan address=\"10.1186/s41100-025-00612-z\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHara K, Takahashi N, Wakamatsu A, Caltabiano S. Pharmacokinetics, pharmacodynamics and safety of single, oral doses of GSK1278863, a novel HIF-prolyl hydroxylase inhibitor, in healthy Japanese and Caucasian subjects. Drug Metab Pharmacokinet. 2015; 30(6): 410\u0026ndash;418. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.dmpk.2015.08.004\u003c/span\u003e\u003cspan address=\"10.1016/j.dmpk.2015.08.004\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eGrote Beverborg N, Verweij N, Klip IT, van der Wal HH, Voors AA, van Veldhuisen DJ, et al. Erythropoietin in the general population: reference ranges and clinical, biochemical and genetic correlates. PLoS One. 2015; 10(4): e0125215. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1371/journal.pone.0125215\u003c/span\u003e\u003cspan address=\"10.1371/journal.pone.0125215\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003ePacker M. How can sodium-glucose cotransporter 2 inhibitors stimulate erythrocytosis in patients who are iron-deficient? Implications for understanding iron homeostasis in heart failure. Eur J Heart Fail. 2022; 24(12): 2287\u0026ndash;2296. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/ejhf.2731\u003c/span\u003e\u003cspan address=\"10.1002/ejhf.2731\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHung SC, Kuo KL, Peng CH, Wu CH, Wang YC, Tarng DC. Association of fluid retention with anemia and clinical outcomes among patients with chronic kidney disease. J Am Heart Assoc. 2015; 4(1): e001480. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1161/JAHA.114.001480\u003c/span\u003e\u003cspan address=\"10.1161/JAHA.114.001480\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSwedberg K, Young JB, Anand IS, Cheng S, Desai AS, Diaz R, et al for RED-HF Committees; RED-HF Investigators. Treatment of anemia with darbepoetin alfa in systolic heart failure. N Engl J Med. 2013; 368(13): 1210\u0026ndash;1219. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1056/NEJMoa1214865\u003c/span\u003e\u003cspan address=\"10.1056/NEJMoa1214865\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eHeidenreich PA, Bozkurt B, Aguilar D, Allen LA, Byun JJ, Colvin MM, et al. 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2022; 145(18): e876-e894. doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1161/CIR.0000000000001062\u003c/span\u003e\u003cspan address=\"10.1161/CIR.0000000000001062\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Table 1","content":"\u003cp\u003eTable 1 is available in the Supplementary Files section.\u003c/p\u003e\n"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"hemodialysis, anemia, erythropoietin, volume overload","lastPublishedDoi":"10.21203/rs.3.rs-7985285/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7985285/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eAnemia in hemodialysis patients is primarily attributed to insufficient erythropoietin production. In patients with heart failure-related anemia, erythropoietin production is often inadequate relative to the hemoglobin level. Therefore, we hypothesized that cardiac stress induced by volume overload in hemodialysis patients might influence endogenous erythropoietin production and anemia status.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eChanges in serum erythropoietin, hemoglobin, total protein, and reticulocyte levels across three consecutive hemodialysis sessions within one week were investigated. All patients were undergoing three times weekly hemodialysis and were not receiving erythropoiesis-stimulating agents or hypoxia-inducible factor prolyl hydroxylase inhibitors. Patients were divided into three groups based on the percentage of body weight gain at the first session of the week, relative to the weight at the end of the previous session (Group A: \u0026gt;5%, n\u0026thinsp;=\u0026thinsp;11; Group B: 3\u0026thinsp;\u0026minus;\u0026thinsp;5%, n\u0026thinsp;=\u0026thinsp;15; and Group C: \u0026lt;3%, n\u0026thinsp;=\u0026thinsp;5).\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eIn Groups A and B, both total protein and hemoglobin levels at the beginning of the second and third sessions were significantly higher than those at the first session, which suggests hemoconcentration due to water removal. However, relative to the level at the beginning of the first session, the serum erythropoietin level at the beginning of the second and third sessions increased more drastically (Group A: 82.5\u0026thinsp;\u0026plusmn;\u0026thinsp;130.3%, and 99.1\u0026thinsp;\u0026plusmn;\u0026thinsp;118.8%; Group B: 79.6\u0026thinsp;\u0026plusmn;\u0026thinsp;130.3%, and 83.0\u0026thinsp;\u0026plusmn;\u0026thinsp;114.6%, respectively) than the total protein (Group A: 4.9\u0026thinsp;\u0026plusmn;\u0026thinsp;2.6%, and 5.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.9%; Group B: 2.6\u0026thinsp;\u0026plusmn;\u0026thinsp;4.0%, and 2.5\u0026thinsp;\u0026plusmn;\u0026thinsp;3.9%, respectively) and hemoglobin levels (Group A: 4.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7%, and 5.5\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1%; Group B: 3.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3%, and 3.2\u0026thinsp;\u0026plusmn;\u0026thinsp;4.3%, respectively). Changes in these parameters in Group C were unremarkable, and changes in reticulocyte count were unremarkable across all groups.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e\u003cp\u003eThe disproportionate increase in the serum erythropoietin level suggests a stimulation of innate erythropoietin production rather than mere hemoconcentration. Endogenous erythropoietin production is stimulated by the excessive water removal necessary to correct volume overload in hemodialysis patients. Further research is needed to elucidate the underlying mechanisms of this erythropoietin stimulation and its potential influence on hematopoiesis and the patient's anemia status.\u003c/p\u003e","manuscriptTitle":"Influence of volume overload on endogenous erythropoietin production in hemodialysis patients","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-20 08:17:04","doi":"10.21203/rs.3.rs-7985285/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"19078781-f77c-4149-884f-2b7030e466e8","owner":[],"postedDate":"November 20th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-02T03:10:24+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-20 08:17:04","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7985285","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7985285","identity":"rs-7985285","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}