Pregnanediol Excretion in Normal Children and in Children With Various Endocrine Disorders, Including Congenital Adrenal Hyperplasia

THE urinary excretion of pregnanediol has for many years been used as an index of progesterone production in the body. Although progesterone may not be the sole metabolic precursor of pregnanediol—administration of desoxycorticosterone has been shown to cause an increase in pregnanediol excretion—the urinary levels of pregnanediol have been found to bear such a close relation to physiologic events and clinical findings as to leave no doubt that they must be a faithful reflection of progesterone secretion. This is the more surprising when it is considered that, even in late pregnancy, progesterone can barely be detected in blood, and not at all in urine. At this time large quantities of pregnanediol are being excreted. Judging by the conversion of exogenous progesterone, the production of endogenous progesterone should be nearly ten times the urinary excretion of pregnanediol. It is therefore likely that once progesterone is set free in the organism, its existence is so evanescent that the direct measurement of circulating progesterone in peripheral venous blood will not be feasible in nonpregnant subjects however much assay techniques are refined. There is thus every reason to suppose that the assay of pregnanediol will continue to hold a pre-eminent place in the assessment of progesterone metabolism.