Serum leptin concentrations in relation to body fat, gender, sex hormones and metabolic covariates in Thais

Abstract

In the present study, the relation of serum leptin to adiposity, gender and metabolic covariates in normal Thais was examined. Subjects consisted of 224 individuals aged between 20 - 79 years. Eighty two were men while 142 were women. Data were expressed as mean ± SEM. Serum leptin was associated with total body fat assessed by dual-energy X-ray absorptiometry in both men (r = 0.80, P < 0.0001) and women (r = 0.73, P < 0.0001). Compared to women, serum leptin concentrations was lower in men (P < 0.0001). The difference still persisted after controlling the adiposity. Compared to premenopausal women, postmenopausal women had higher serum leptin independent of adiposity (P < 0.0001). In men, serum free testosterone was negatively associated with serum leptin (r = -0.36, P < 0.001) while there was no association between serum estradiol and leptin. The relation between serum FT and leptin in men no longer persisted after controlling for adiposity. Body fat was associated with fasting insulin levels in both men (r = 0.26, P < 0.05) and women (r = 0.18, P < 0.05). However, the association between fasting insulin levels and body fat in both men and women no longer existed after adjusting for leptin. We concluded that serum leptin concentrations are associated with total body adiposity and serum leptin may mediate the effect of body fat on insulin sensitivity. There appears to be a sexual dimorphism of serum leptin unrelated to sex hormone status and the amount of body fat.