TESTOSTERONE DECREASE AND OESTROGEN INCREASE IN MALE PATIENTS WITH OBESITY

Abstract
The concentration of sex hormones and their binding in the plasma were measured in male patients (20-40 yr old), who weighed 140-170% (I), 170-200% (II) and > 200% (III) of their ideal weight. Correlated to body weight, there is a reduction in the total concentration of testosterone [T], which, in the very obese patients, amounts to 41% (in group I: 85%, in group II: 68%; P < 0.001) of that found in an age-matched healthy control group of subjects of normal body weight (90-115% of the ideal body weight; n: 20). Androstenedione values show only a trend downwards (from 0.94 to 0.72 ng/ml plasma), while the estrogen values increase significantly; estrone increases by a factor of 1.09 (I), 1.43 (II; P < 0.001) and 1.69 (III; P < 0.001) and estradiol [E2] by 1.13, 1.43 P < 0.001) and 1.76 (P < 0.001), respectively. Despite the fall in T there are no clinical signs of hypogonadism, as SHBG [sex hormone-binding globulin] (from 5.1 .+-. 0.8 in the controls to 2.4 .+-. 0.6 .times. 10-8 M in the very obese patients of group III) and the protein-bound fraction of T also decrease. As a result, the concentration of free T remains constant (120 pg/ml), except in the very obese (93 pg/ml). Because of the different affinity of the binding proteins for T and E2 the ratio of free E2:free T shifts less strongly in favor of the feminizing hormone (11.1 .times. 10-3 in group III as compared to 4.1 .times. 10-3 in the controls), than is suggested by the total hormone concentrations. A disturbance in the gonadal function of the pituitary gland or the testes is not present, since the concentration of LH [lutropin] is normal and the testicular response to hCG [human chorionic gonadotropin] in very obese patients adequate (increase of T by a factor of 3.11 as compared to 2.23 in the controls). The cause of the decrease in T and SHBG is unknown, while the increase of plasma estrogens is likely to be due to the increased conversion of androgens to estrogens in the adipose tissue, which clearly plays an important role for plasma concentrations of sex hormones in obese patients.