In obese men, sex hormone-binding globulin (SHBG) as well as total testosterone (TT) levels are decreased. Data concerning serum free testosterone (FT) levels in obese men are discordant. FT levels are decreased in only some morbidly obese men consistent with an impairment of the feedback regulatory mechanism. It has been suggested that a functional decrease of LH pulse amplitude and serum LH levels are reflected in their hypoandrogenism. We have studied two groups of obese men (Group 1: BMI <FONT FACE=Symbol>£</FONT> 35kg/m² and Group 2: BMI > or = 35.1kg/m²) before and after six months of a low calorie diet (1200kcal/day), Every patient received a therapeutic prescription of dexfenfluramine (15mg b.i.d.) that was maintained for six months. Plasma insulin levels, serum total testosterone, free testosterone and LH concentrations were obtained before and after weight loss. Moderately obese men (BMI = 32.3 ± 1.9kg/m²) presented significantly decreased TT levels (390 ± 120ng/dL) as well as FT (mean ± SD: 16.0 ± 4.8pg/mL) as compared with normal controls. Serum LH concentrations (4.5 ± 2.9mlU/mL) were normal. Insulin levels were elevated in all patients (46,3 ± 30.1 muU/mL). After weight-loss there was a significant (p < 0.01) increase in TT, FT and LH levels whereas insulin concentrations significantly decreased, In massively obese men (BMI = 43.0 ± 6.7kg/m2) TT (320 ± 110ng/dL), FT (11.0 ± 2.1pg/mL) and LH (3.1 ± 1.3mlU/mL) were decreased and significantly lower as compared with the previous group and normal controls. As expected, after weight loss as expected, TT, FT and LH levels increased significantly while insulin concentrations decreased. We concluded that FT levels are dependent on the degree of obesity, massively obese men (BMI > or = 35.1kg/m²) being considered as candidates for consistently low FT levels.
Testosterone; Hypogonadism; Obesity; Weight loss; Insulin; Gonadostate
