Androstenedione may be a more important precursor of tissue dihydrotestosterone than testosterone in women.

The expression of androgenic features in the external genitalia and skin is largely dependent on the intracellular formation of dihydrotestosterone (DHT). The relative contributions of androstenedione (delta 4A) and testosterone (T) to DHT production in skin have not been compared. To clarify this, the authors studied the in vitro conversion of delta 4A to DHT, delta 4A to T, and T to DHT in genital and/or pubic skin minces from 20 normal women, 4 hirsute women, and 3 normal men. In normal women, the mean conversion ratios (CRs) of delta 4A to DHT in genital skin (7.06% +/- 1.72%, standard error of the mean) and in pubic skin (2.30% +/- 0.26%) were both significantly higher (P less than 0.05) than the respective mean CRs for T to DHT in genital and pubic skin (3.53% +/- 0.68% and 0.74% +/- 0.14%). In hirsute patients, the data suggested a higher CR of delta 4A to DHT (10.6% +/- 4.59%) compared with T to DHT (4.17 +/- 1.07). Conversely, the CR of delta 4A to DHT (12.8% +/- 9.8%) was significantly lower than the CR of T to DHT (59.7% +/- 12.0%) in male genital skin (P less than 0.01). Since daily blood production rates and serum concentrations of delta 4A are higher than T in women, it is concluded that delta 4A may be a more important precursor for DHT in female skin.