Serum angiotensin-converting enzyme activity in pregnancy-induced hypertension.

Angiotensin-converting enzyme (ACE) activity was measured in the serum of 33 pregnant women with normal blood pressure or pregnancy-induced hypertension (PIH) using sensitive hippuric acid colorimetric micromethods. Mean serum ACE activity in 17 PIH patients (73.25 +/- 18.81 U/ml) was significantly higher than that in normotensive pregnant women (16 cases; 52.36 +/- 9.91 U/ml; p less than 0.01). Mean arterial blood pressure was correlated with the level of serum ACE activity in all pregnant women (y = 69.089 + 0.49x, r = 0.562, p less than 0.01). In PIH patients, the gestosis index and the degree of edema also had a statistically significant correlation with the level of serum ACE activity (y = -0.560 + 0.056x, r = 0.549, p less than 0.05; y = -1.760 + 0.043x, r = 0.629, p less than 0.01). The amount of 24-hour urinary protein was independent of the level of serum ACE activity. It seems that a disturbance in the regulation of ACE activity may be one of the factors responsible for the development of PIH.