Plasma renin activity in pregnant women with oedema treated with hydrochlorothiazide.

Fourteen pregnant women with oedema and inappropriate weight gain were treated with hydrochlorothiazide, 50 mg daily. Plasma renin activity (PRA) increased form 2.89 +/- 0.44 (mean +/- SEM) to 10.46 +/- 1.61 ng/ml/h after one week and remained high (10.07 +/- 1.36 ng/ml/h) after three weeks of drug therapy. Eight women were considered to be "responsers" because of a marked increase of PRA) (greater than 9.5 ng/ml/h) and six subjects ranked as "weak responders", with PRA increases of less than 6.0 ng/ml/h. These subgroups had different patterns of sodium excretion, weight loss and systolic blood pressure. The different reactivity of the renin-angiotensin system suggests that there may be at least two, basically different, types of pathophysiology in pregnancy associated edema.