[Determination of plasma and urinary estrogens by use of a new enzyme method]

The transhydrogenase function of the oestradiol dehydrogenase of human placenta is used in such a condition as the transhydrogenase activity is directly related to oestrone and oestradiol concentration. The method is highly specific. Reacting oestrone with hydrazin before the assay allows specific determination of oestradiol. The limit of sensitivity is 10 picograms (precision 10%) in plasma and 1 microgram in urine (precision 10%). The determination is done directly on hydrolyzed urine without extraction and is rapid and highly specific. The method seems to be competitive for oestrogen radioimmuno assay in plasma and offers great advantages towards conventional chemical methods in urine. Repetitive profiles of urinary oestrogen excretion can be obtained easely.