Androgens in Health and Disease.pdf - E Library

124 Legro
Fig. 1. The spectrum of phenotypes for various androgen excess disorders.
Fig. 2. The triumvirate of androgen action. SHBG, sex hormone-binding globulin; 5–α Red, 5αreductase;
CYP1B1, cytochrome P450, subfamily 1, polypeptide 1.
is the preferential source of testosterone, and it is estimated that 75% of circulating
testosterone originates from the ovary (mainly through peripheral conversion of
prohormones by liver, fat, and skin, but also through direct ovarian secretion). Androstenedione,
largely of ovarian origin, is the only circulating androgen that is higher in
premenopausal women than men, yet its androgenic potency is only 10% of testosterone.
DHT is the most potent androgen, although it circulates in negligible quantities,
and results primarily from the intracellular 5α-reduction of testosterone. In the past,
measurement of 3α-androstanediol glucuronide, a peripheral metabolite of DHT was
used as a circulating marker of androgen excess in the skin (hirsutism and acne), but
its clinical use is negligible.