The role of 19-hydroxy-delta4-androstene-3,17-dione in the conversion of circulating delta4-androstene-3, 17-dione to estrone.

A mixture of 4-14C-delta4-androstene-3, 17-dione and 6,7-3 H-19-hydroxy-delta4-androstene-3, 17-dione was intravenously injected into three women, and the 3H/14C ratios in urinary 19-hydroxyandrostenedione and urinary estrogens were determined. The ratios of 3H/14C in the estrogens were similar to those of the dose, while the ratios in urinary 19-hydroxyandrostenedione were mcuh higher than those of the dose. The fractional conversions of androstenedione to estrone and of 19-hydroxyandrostenedione to estrone are therefore similar. However, little, if any, 19-hydroxyandrostenedione produced during aromatization enters the circulation and mixes with injected 19-hydroxyandrostenedione.