Decreased androgen levels in massively obese men may be associated with impaired function of the gonadostat

OBJECTIVE: In obese men, sex hormone-binding globulin (SHBG) as well as tot al testosterone (TT) levers are decreased. Data concerning serum free testo sterone (FT) levels in obese men are discordant. FT levels are decreased in only some morbidly obese men, consistent with an impairment of the feedbac k regulatory mechanism. In this study we aimed to verify serum levels of TT and FT in two groups of obese men (BMI <35.0 kg/m(2) and BMI > 35.1 kg/m(2 )) before and after weight loss. DESIGN: Two groups of obese men (group 1: BMI less than or equal to 35 kg/m (2); and group 2: BMI greater than or equal to 35.1 kg/m(2)) were studied b efore and after 6 months of a low energy diet (1200 kcal/day). Every patien t received a therapeutic prescription of dexfenfluramine (15 mg b.i.d.) tha t was maintained for 6 months. SUBJECTS: Thirty seven obese men and 20 normal weight men. MEASUREMENTS: Serum sex hormones (TT and FT), serum luteinizing hormone (LH ) and insulin were analyzed by RIA assays. Plasma insulin levels, serum TT, FT and LH concentrations were obtained before and after weight loss. RESULTS: Moderately obese men (BMI = 32.3 +/- 1.9 kg/m(2)) presented signif icantly decreased TT levels (390 +/- 120 ng/dl) as well as FT (mean +/- s.d .: 16.0 +/- 4.8 pg/ml) as compared with normal controls. FT serum levels ha d a significant and negative correlation with body mass index (BMI), wherea s for TT concentrations this correlation was not significant. Serum LH conc entrations (4.5 +/- 2.9 mlU/ml) were normal. Insulin levels were elevated i n all patients (46.3 +/- 30.1 muU/ml). After weight loss there was a signif icant (P < 0.01) increase in TT, FT and LH levels, whereas insulin concentr ations significantly decreased. In massively obese men (BMI = 43.0 +/- 6.7 kg/m(2)), TT (320 +/- 110 ng/dl), FT (11.0 +/- 2.1 pg/ml) and LH (3.1 +/- 1 .3 mlU/ml) were decreased and significantly lower as compared with the prev ious group and normal controls. As expected, after weight loss TT, FT and L H levels increased significantly while insulin concentrations decreased. CONCLUSIONS: We concluded that FT levels are dependent on the degree of obe sity, massively obese men (BMI <greater than or equal to> 35.1 kg/m(2)) bei ng considered as candidates for consistently low FT levels. A functional de crease of LH pulse amplitude and serum LH levels as well as a possible nega tive action of excess of circulating leptin on the steroidogenesis may be r elated to the decreased androgens levels in massively obese men.