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 low testosterone level and whether the FLI was the strongest risk factor for low testosterone level in two different age groups. METHODS: Two cross-sectional studies were performed. A total of 3,443 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 total testosterone (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 low 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 low 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 odds ratio of low testosterone level in patients with potential hepatic steatosis was 4.26 (1.57–11.60) after adjusted for age and homeostasis model assessment of insulin resistance (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 low testosterone level independent of insulin resistance in male populations of different ages; however, the association can be modulated by SHBG levels in the young. SIGNIFICANCE STATEMENT: In the study, FLI was the strongest negative risk factor for low testosterone level in the Chinese adult male population. The results suggested that hepatic steatosis assessed by the FLI was the main risk factor for male low testosterone level, independent of age, insulin resistance, smoking, and drinking status; however, the association of FLI and TT levels can be modulated by SHBG levels. Taken together these findings indicate that clinical physicians should pay more attention to the FLI index and hepatic steatosis, so that they can take advantage of them for assessing the risk of developing of low testosterone level in the male population.