delta 4-3-Ketosteroid 5 alpha-oxidoreductase in human uterine leiomyoma.

Homogenates of human endometrial, myometrial, and leiomyoma tissues were incubated with (1,2,6,7-3H)-testosterone, and 3H-dihydrotestosterone was subsequently identified, indicating the presence of the enzyme delta 4-3-Ketosteroid 5 alpha-oxidoreductase. The enzyme activity of leiomyoma was higher than that of endometrial and myometrial tissue, while endometrial activity was higher than myometrial activity. The results raise the possibility that 5 alpha-reduced androgens may play a role in the pathophysiology of uterine leiomyoma.