Surgically confirmed severe endometriosis is associated with lower risk of steatotic liver disease: Evidence of estrogen-linked hepatic-reproductive crosstalk

OBJECTIVE: The prevalence of steatotic liver disease (SLD) is increasing globally. Endometriosis, affecting up to 10% of women, is a major cause of infertility. While associations between endometriosis and metabolic syndrome have been reported, its relationship with SLD remains unclear. Our study aimed to evaluate the association between endometriosis severity and SLD. METHODS: We retrospectively analyzed women who underwent surgery for endometriosis with documented revised American Society for Reproductive Medicine scores at a tertiary hospital (January 1, 2009, to February 28, 2025) and had undergone abdominal computed tomography (CT) within 6 months as part of the clinical evaluation for endometriosis. Hepatic steatosis was assessed on abdominal CT using the liver-to-spleen Hounsfield unit (LS) ratio with predefined cutoff values, where lower values indicate greater hepatic fat accumulation, and SLD and severe SLD were defined as LS <1.0 and <0.8, respectively. The hepatic steatosis index (HSI) was used for sensitivity analysis. RESULTS: Among 455 patients, 232 had severe endometriosis (SE, stage 4) and 223 had non-severe endometriosis (NSE). Baseline characteristics were similar between groups, except for higher estradiol levels in the SE group (P < 0.001). The prevalence of SLD was significantly lower in SE (48.3%) compared to NSE (62.3%) (P = 0.002), and severe SLD was less common in SE (8.2% vs 16.1%, P = 0.009). Patients with SLD exhibited lower estradiol levels than those without, suggesting a potential protective effect of estradiol on hepatic steatosis. Multivariate analysis confirmed that SE was independently associated with a reduced risk of SLD, irrespective of age, body mass index, and metabolic comorbidities. CONCLUSIONS: SE was associated with a lower prevalence of SLD, potentially mediated by higher estradiol levels.