Serum angiotensin converting enzyme activity in normal adults and patients with different types of hypertension

The serum converting enzyme activity (SCEA) was measured in 86 healthy individuals (1.44±0.82 u, mean ± sd), 39 patients with essential hypertension (1.53±0.71 u), 7 patients with hypertension due to renal artery stenosis (1.76±0.77 u), 14 patients with chronic renal failure (2.10±0.57 u), 7 patients with renal failure and hypertension (2.62±0.35 u), 22 normotensive pregnant women (1.02±0.26 u) and 6 hypertensive pregnant women (1.1±0.3). No difference was detected between men and women or between normotensives and hypertensives. Howevery, a significant rise in SCEA was found in patients with chronic renal failure (P<0.005), in whom an enlarged pulmonary vascular bed and accelerated cellular breakdown are thought to be the causes of the elevated SCEA. During pregnancy, subnormal SCEA was found (P<0.005), and this is thought to be due to the enzyme consumption in the kinin system, which is activated during pregnancy. We assume that converting enzyme is not a limiting factor in angiotensin conversion, and most probably it does not contribute significantly to the pathogenesis of hypertension.