Sex-hormone-binding globulin in clinically hyperandrogenic women: association of plasma concentrations with body weight.

The relationship of sex-hormone-binding globulin (SHBG) with actual body weight (ABW), ideal body weight (IBW), ABW as percentage of the IBW (% IBW), Quetelet index (weight/height2) and plasma concentrations of various androgens and 17 beta-estradiol (E2) were studied in 9 normal and 57 hirsute patients (group 1). In hirsute patients, plasma levels (ng/dl, mean +/- standard error of the mean [SEM]) of testosterone (T; 77 +/- 4), dihydrotestosterone (DHT; 26 +/- 2), androstenedione (delta 4A; 184 +/- 16), and SHBG (0.91 +/- 0.05 micrograms DHT/dl) but not of dehydroepiandrosterone (DHA; 608 +/- 55) and E2 (6.1 +/- 0.1) were significantly different from those in controls. A negative correlation was observed between SHBG and ABW, both in controls (P less than 0.05) and hirsute patients (P less than 0.01). The hirsute patient population was subdivided into two groups: nonobese (group 2; 60 +/- 1 kg; n = 35) and obese (group 3; 96 +/- 2 kg; n = 22). Plasma androgens, T/SHBG (an index of free T) and E2 in groups 2 and 3 (T: 75 +/- 4, 81 +/- 7; DHT: 24 +/- 2, 28 +/- 3; T/SHBG: 85 +/- 7, 105 +/- 11; delta 4A: 203 +/- 13, 155 +/- 16; DHA: 663 +/- 83, 521 +/- 49; E2: 6.1 +/- 1.0, 5.8 +/- 0.9) were similar; yet SHBG in group 3 (0.75 +/- 0.04) was significantly lower than in group 2 (1.0 +/- 0.01). Inverse correlations between SHBG and ABW, % IBW, and ABW/H2 were observed in group 2 but not in group 3. We conclude that a negative relationship exists between SHBG and the body size in nonobese women and that in hirsute patients, obesity leads to a further lowering of SHBG through mechanism(s) probably independent of androgens.