The postural plasma renin activity response in essential hypertension and primary hyperaldosteronism

Supine and standing values of plasma renin activity (PRA) and colloid osmotic pressure (COP) were measured in 20 essential hypertensive patients, including five malignant cases, and in five patients with signs of primary hyperaldosteronism. The groups were compared mutually and to 22 normal controls of corresponding age and sex. Mean supine plasma renin activity (PRA) in essential benign hypertensives was significantly higher than normal. Mean supine PRA in malignant essential hypertensives was significantly higher than in benign essential hypertensives. Mean supine PRA in primary hyperaldosteronism was significantly lower than in benign essential hypertensives. In hypertensives with grade I-III a significant linear correlation between Δplasma colloid osmatic pressure and ΔPRA appeared. The slope of the line was significantly less than the line for normal controls, signifying a lesser postural response of PRA in this group. In this respect there was no distinction between essential hypertensives and patients with primary hyperaldosteronism. The decreased postural PRA response is considered to be a sequel to the hypertensive state.