[Serum and tissue 17 beta hydroxysteroid dehydrogenase and estrogens in hydatidiform mole]

The activity of 17 beta hydroxysteroid dehydrogenase (EC 1.1.1.62) in hydatidiform mole tissue and in sera from women with molar pregnancies was determined and compared with that of women with normal pregnancies. Oestradiol and oestrone concentrations were also estimated in plasma in both cases. Very early in the pregnancy, the enzyme activity in tissues and sera, and the concentrations of oestradiol and oestrone were the same in normal and molar gestations. In more advanced pregnancies, the enzyme activity and the concentration of oestrogens were higher in molar pregnancies at the same stage of development. The 17 beta hydroxysteroid dehydrogenase seems to be identical in placenta and in molar tissue if Km values and polyacrylamide gel separations are taken into consideration, i.e. the differences measured are essentially quantitative.