Of 53 women referred for study of hypertension 16 were taking estrogen-gestagen combinations. When oral contraceptives were discontinued blood pressure declined gradually over a period of 1 to 3 months. Of 11 patients who had a normal blood pressure before taking estrogen-gestagen 5 patients have maintained blood pressure within normal limits for 6 months or longer after medication was withheld. In the remaining patients blood pressure has fallen to lower levels than those observed on estrogen-gestagen combinations but remains above the upper limits of normal.
Administration of an estrogen-gestagen comregularly increased the concentration of angiotensinogen (the substrate of the enzyme renin) in plasma. The generation of angiotensin was enhanced by higher substrate concentration. Plasma renin activity was consistently higher during oral contraceptive administration than after discontinuing medication. The effect of medication was evident both during sodium loading and in sodium-depleted patients, and the normal response of plasma renin activity to standing was present. Very high plasma renin activity, not suppressed by sodium loading, was found in some patients with diastolic blood pressures above 115 mm Hg.
Aldosterone secretion and excretion rates were higher during estrogen-gestagen administration than after the medication was withheld. Aldosterone levels were correlated with plasma renin activity.
The relationship between these laboratory findings and the development of hypertension in susceptible individuals is not clearly defined. The changes in plasma renin activity and aldosterone induced by oral contraceptives must be taken into account in evaluating studies on hypertensive patients.
Blood pressure should be followed in patients receiving an oral contraceptive. An alternative method of contraception is advisable if a significant and persistent increase in blood pressure appears during administration of an estrogengestagen combination.