Plasma precursors of estrogen. III. Conversion of plasma dehydroisoandrosterone to estrogen in young nonpregnant women.

The utilization of plasma dehydroisoandrosterone for estrogen production was studied in 4 normal young nonpregnant women and in one young surgical castrate woman. The mean transfer constant for total conversion to estrogen, [sigma] DE-BU' was 0.0016 of which about one third (0.0005) could be accounted for by conversion of dehydroisoandrosterone first to plasma androstenedione which in turn was converted to estrone. The remaining fractional conversion appeared to result principally in estradiol formation via a pathway probably not involving plasma androstenedione. The conversion of plasma dehydroisoandrosterone to estrogen was similar in the surgical castrate to that observed in the ovulating women. It is concluded that plasma dehydroisoandrosterone is converted to estrogen at extraglandular site(s) but this contribution represents only a minor fraction of total estrogen production in normal young women.