Pre-chronic kidney disease -- Serial creatinine tracks glomerular filtration rate decline above 60 mL/min

ABSTRACT OBJECTIVES Primary care for chronic kidney disease (CKD) stage 1-2 has recently been shown to slow CKD progression. We describe an approach to detect early decline in glomerular filtration rate (GFR) above 60 milliliters per minute (mL/min), before CKD stage 3. METHODS We re-examined a standard reference that found low tubular secretion of creatinine (TScr) at GFRs above 80 mL/min and suggested “…observation of subtle changes in serum creatinine levels”. We explain why that method extends down to 60 mL/min and summarize why estimated GFR (eGFR) is unreliable above 60 mL/min. RESULTS Four patient cases show how serum creatinine (sCr) referenced to an individual’s historical maximum suggests increased risk, triggering investigation to separate benign processes that alter sCr from decline in GFR of prechronic kidney disease (preCKD). CONCLUSIONS At GFRs above 60 mL/min, serial creatinine is more reliable than GFR estimating equations and appears practical for ‘race-free’ clinical monitoring and early intervention. STRENGTHS OF THIS STUDY Includes serial creatinine proof-of-concept cases that show preCKD Reviews ‘race-free’ properties that favor serial creatinine for early kidney disease Addresses mathematical limitations of GFR estimating equations Re-analyzes a 40-year-old standard reference that still influences research, showing its overlooked importance for CKD stage 1-2