Pregnanediol Determinations in the Clinic and in Research*

PREGNANEDIOL was first isolated by Marrian (1) in 1929, when he was engaged in thepurification of “oestrin” from pregnancy urine. He described the properties of this new “unidentified solid alcohol” very precisely, and his first analyses came surprisingly near to the right formula, C21H36O2,at a time when the greater part of steroid chemistry was still unknown. To-day, looking back on twenty years of chemical, biologic, and clinical research, it is comparatively easy to see the principal features of the interesting pattern which centers around the pregnanediol molecule. The first clue to the biologic significance of pregnanediol is given by its structural formula which shows a striking resemblance to that of the corpus luteum hormone, progesterone. Pregnanediol is nothing else but reduced progesterone, with all the double bonds of the latter saturated by hydrogen. Thus, the obvious inference would be that urinary pregnanediol is a metabolite of progesterone. This important fact is the reason why so many workers are interested in pregnanediol determinations.