[en] The determination of free steroids would be preferable with respect to total hormone plasma content, since it yields more reliable information about the most biologically active form of circulating steroids. The authors report a method for the determination of apparent free progesterone concentration (AFPC) in plasma, by means of direct radioimmunoassay of dialyzed progesterone after equilibrium dialysis. (Auth.)

[en] Elevated plasma levels of an endogenous factor with digoxin-like immunoreactivity (DLIS) was recently found in pregnant women, and it has been postulated to play a role in the regulation of fluids and electrolytes, as well as in the pathogenesis of hypertensive disorders in pregnancy. The authors have studied the plasma levels of DLIS in normal women (before and after treatment with contraceptive pills) and in pregnant women (either normotensive or hypertensive), during the gestional and the post-partum period using a sensitive RIA method. In addition, the authors have measured the inhibition of binding activity of ³H-ouabain to intact erythrocytes in 7 plasma samples collected from healthy adults and in 5 plasma samples of women in the second or third trimester of pregnancy. In 8 normal cycling women DLIS levels were similar during the follicular phase (24.9±6.2 pg/ml d.e.) and the luteal phase (22.6±4.7 pg/ml d.e.9. Six months treatment with different preparations of contraceptive pills did not affect the concentrations of DLIS. In a cross-sectional study performed on 171 healthy pregnant women a significant increase (p<0.001) of DLIS plasma levels was observed throughout pregnancy, while a decrease was found after the delivery. A significantly higher (p<0.01) mean level of ³Houbain extracts of pregnant women as compared to normal adults, with a significant correlation between the data obtained with RIA and RRA method. On the other hand, no significant differences in DLIS levels were found between singleton and 9 twin pregnancies, and also between non-hypertensive and 8 hypertensive pregnant women. This data confirm that the plasma concentration of an endogenous factor (or a group of substances) with cardiac glycoside-like activity is significantly increased in pregnant women. However, further studies are necessary to well charcterize the possible role of DLIS in the pathphysiology of hypertension in pregnancy