Supplementary Material for: The Fatty Liver Index, the Strongest Risk Factor for Low Testosterone Level

Introduction: The study aimed to determine if hepatic steatosis assessed by Fatty Liver Index (FLI) was an independent risk factor for male testosterone insufficiencylow testosterone level and whether the FLI was the strongest risk factor for testosterone insufficiencylow testosterone level in two different age groups. Methods: Two cross-sectional studies were performed. A total of 3443 male participants (aged 46-75) were recruited into study A (part of lONgitudinal study (REACTION)). Then a total of 267 male participants (aged 25-45) were recruited into study B. Serum TT and sex hormone-binding globulin (SHBG) levels, indicators for assessing hepatic steatosis were measured. The Pearson correlation and regression analysis were performed to investigate the risk factors for testosterone insufficiencylow testosterone level. Results: The FLI had the strongest negative correlation with serum testosterone in the study A (r=-0.436) and B (r=-0.542). Compared with patients with a FLI lower than 30, the risk for testosterone insufficiencylow testosterone level increased by 3.48–fold in subjects with a FLI higher than 60 adjusted for potential risk factors in study A. In study B, the OR of testosterone insufficiencylow testosterone level in patients with potential hepatic steatosis was 4.26 (1.57-11.60) after adjusted for age and HOMA-IR, and 0.59 (0.14-2.60) after adjusted for age, HOMA-IR, waist circumference, body mass index, and SHBG. Conclusions: FLI, was the strongest risk factor for male testosterone insufficiencylow testosterone level independent of insulin resistance in a male populations of different ages, however the association can be modulated by SHBG levels in the young.