Angiotensin converting enzyme activity in hypertensive pregnancy

Recent investigations suggest angiotensin converting enzyme (ACE) activity is generally decreased in normotensive pregnancy, but less is known about the level of activity of this enzyme in hypertensive pregnant subjects. The primary source of ACE is vascular endothelium and it can be measured in serum or plasma. In a preliminary investigation, we measured and compared diastolic blood pressure and serum ACE activity in 14 uncomplicated pregnant subjects during the third trimester, and in 16 subjects of similar gestation duration hospitalized with pregnancy-induced hypertension PIH. No patient had a positive history for, or evidence of, pulmonary or other metabolic disease. Compared with levels in normal pregnancy, serum ACE activity was found to be significantly elevated in PIH. In this study, this increase was not due to differences between the groups in maternal chronologic age or gestational duration. Further studies are necessary to determine if the increase in ACE activity precedes or follows development of clinically apparent PIH. If the former is the case, ACE activity might be a useful indicator of risk for PIH.