Plasma Androgens and Sex Hormone-Binding Globulin in the Evaluation of Hirsute Females

Abstract

Hirsutism is usually associated with increased testosterone (T) production and metabolic clearance rates. Considerable overlap of plasma T occurs between hirsute and normal groups. Plasma levels of sex hormone-binding globulin (SHBG) and the factor T/SHBG might separate hirsute patients from normal subjects better than plasma T. A group of 39 hirsute females and 22 normal ovulatory control subjects were studied. Plasma T, androstenedione, and dehydroepiandrosterone were measured by radioimmunoassay; apparent free T (AFT) by equilibrium dialysis; and SHGBG by a method based on saturating the binding sites by labeled dihydrotestosterone. Mean levels of androgens and SHBG of the hirsute patients were significantly different from those of the normal subjects (P less than 0.01). Positive linear correlations were observed between T and AFT, T/SHBG and AFT, and T/SHBG and T; a negative correlation was observed between T/SHBG and SHBG, but no correlation was observed between SHBG and T or AFT. Thirty (77%) of the patients had elevated T/SHBG factors and 28 (72%) had suppressed SHBG levels. Only two patients (5%) had hirsutism associated with normal levels of androgens, SHBG, and T/SHBG. We conclude that SHBG and the factor T/SHBG separate the hirsute population better than any of the androgens studied.