Conversion of progesterone from the adrenal or ovary to deoxycorticosterone in plasma

The in vivo conversion of progesterone to deoxycorticosterone (DOC) by peripheral 21 hydroxylation was studied in normal men and women. The technique used was to infuse labeled progesterone under steady state conditions and isolate the precursor and product from blood by multiple chromatography steps. DOC was chromatographed as both the steroid and its acetylated derivative. The conversion rate was found to be 1.3 +/- 0.1% in men and women despite differences in the concentration of progesterone during the cycle. Since progesterone was very low in men and women in the follicular phase of the cycle, we conclude that DOC is derived from direct secretion. However, progesterone rises to 1073 +/- 101 ng per dl in the luteal phase and the calculations indicate that DOC increases from 8.3 +/- 0.4 (SE) to 15.6 +/- 1.3 ng per dl. 3/4 of luteal phase DOC is from conversion of progesterone. Acute ACTH increases both progesterone and DOC, and almost all of the DOC in plasma is from direct secretion. However, chronic ACTH excess and adrenal 21 hydroxylase deficiency is associated with a fraction (1/4-1/5) of DOC from progesterone indicating that the peripheral conversion rate is unrelated to the adrenal enzyme defect.