Relationship between body composition, sex hormones and leptinemia in hemodialyzed patients with chronic renal failure

Background: Females are characterized by significantly higher plasma leptin concentration than males. It seems likely that sex hormones influence leptinemia independently from differences in body composition. The aim of the present study was to analyze the contribution of plasma concentrations of testosterone and estradiol on leptinemia in hemodialyzed patients. Methods: 110 hemodialyzed patients - HD (60 M, 50 F) and 70 healthy subjects (HS) (30 M, 40 F) were enrolled in this study. Plasma leptin, testosterone or estradiol and CRP concentrations and body composition by dual-energy X-ray absorptiometry (DEXA) were assessed. Results: Total body fat was significantly higher in females than in males (27.5 ± 1.5% vs. 17.2 ± 1.0% of body weight in HD and 36.0 ± 1.0% vs. 18.2 ± 1.4% in HS, respectively). Plasma leptin concentrations were markedly higher in females than in males both in HD (27.9 ± 5.4 ng/ml vs. 9.6 ± 1.9 ng/ml) and HS (16.5 ± 1.7 ng/ml vs. 3.1 ± 0.4 ng/ml). A highly significant, strong positive correlation was found between total fat mass (TFM) and leptinemia in all studied groups. No significant univaried correlation between plasma leptin and testosterone or estradiol concentrations respectively was found both in HD and HS. Multiple regression analyses showed that the main determinant of leptinemia is TFM (β = 0.623 and 0.798 in HS females and males respectively, and β = 1.058 and 0.797 in HD females and males respectively). Plasma concentration of testosterone (β = -0.139 and β = -0.075 in male HD and HS respectively) and estradiol (β = 0.199 and β = 0.046 in females HD and HS, respectively) contributed to leptinemia only in a minor degree. Conclusion: Both testosterone and estradiol are minor contributors to leptinemia both in HS and HD patients. The main determinant of leptinemia in these subjects is total body fat mass.