Serum leptin, gonadotropin, and testosterone concentrations in male patients with anorexia nervosa during weight gain

Amenorrhea in female patients with anorexia nervosa is associated with low leptin secretion, thus suggesting a causal link. In an attempt to address t he hypothesis that leptin also influences the hypothalamo-pituitary-gonadal function in males, we studied three male patients with acute anorexia nerv osa longitudinally. Serum levels of leptin, LEI, FSH, testosterone, and SHB G were measured on a biweekly basis during weight gain. Leptin levels at lo w body mass index values were below the 5th per centile. During weight gain , leptin levels reached or surpassed the 95th percentile. The temporal dyna mics of body mass index and fat mass were closely related to those of lepti n concentrations in serum. Leptin. increments mere paralleled by increments of gonadotropins, testosterone, and the free androgen index (FAI). In each of the patients, serum concentrations of leptin were positively correlated with those of testosterone(P = 0.0001, P: = 0.01, P = 0.07 respectively) a nd FAI (P = 0.0001,P = 0.0001, P = 0.09, respectively). In addition, in the combined data set of all patients changes of leptin over time were positiv ely correlated with changes in LH (P = 0.01), FSH (P = 0.0001), testosteron e (P = 0.002), and FAI (P = 0.002) In conclusion, these data suggest that l eptin might also play an important role in the regulation of the hypothalam o-pituitary-gonadal axis and fertility in underweight males as has previous ly been shown in underweight females.