[Renin and aldosterone during pregnancy (author's transl)]

Systematical determination of renin activity (PRA) and aldosterone concentration (PA) in blood of normal and hypertensive pregnant women was done. At the same time, reactive change of PRA and PA to NaCl loading was studied, and the authors gained the following conclusions: 1) In normal pregnant women a significant increase was observed respectively in PRA and PA in comparison with those observed in non-pregnant status (PRA: P less than 0.05, PA: P less than 0.02). A peak (11.85 ng/ml/hr) was formed in PRA at the 32nd week of pregnancy, while in PA an increase lasted until the start of labour, attaining a level of 563.3 pg/ml (mean value). 2) PRA and PA in toxemia of pregnancy were obviously lower in comparison with normal pregnancy in the corresponding period. Analysis by the two dimensional cordinate system in which PA value was represented by axis of abscissas and PRA value by axis of ordinate disclosed that hypertensive toxemia of pregnancy tended to be distributed among patients with low PRA while non-hypertensive toxemia of pregnancy was distributed among patients with low PA. 3) In non-pregnant women and those in the first trimester, no noticeable change was displayed by NaCl load either in PRA or in PA, but the reactivity became obvious along with advancement of pregnancy and a high reactivity was shown by pregnant women who were positive in the so-called roll-over test. Also when women whose blood pressure rose to 140/90 mmHg or above after NaCl loading were classified as those positive in NaCl loading test, all the normal pregnant women were negative, but among the patients with hypertensive pregnancy, a positive reaction was represented in half of them in spite of the treatment. The above signifies that the PRA and PA were different in their behaviors in the third trimester, and in the value of PA, participation of aldosterone deriving from fetus was suggested. Analysis of PRA and PA by the two dimensional cordinate system and analysis of the behavioral reaction in NaCl loading test were supposed to be clinically useful for classification of the clinico-pathological types of toxemia of pregnancy.