The postural plasma renin response in renovascular hypertension.

Abstract

Abstract. Plasma renin activity (PRA) in the supine position has been measured in 20 patients with signs of renovascular hypertension. Aldosterone secretion rate (ASR) was measured in 11 of these patients, while postural experiments were performed in 16. Operation, mostly reconstruction of the renal artery, was performed in 16 patients. PRA in the supine position was on average significantly higher in the patients than in normal subjects, although the range of values in the two groups overlapped. Postural experiments demonstrated qualitative as well as quantitative deviations from normal. When the increase in colloid osmotic pressure (ΔCOP) was plotted against the increase in PRA (ΔPRA), a highly exaggerated PRA response was detected in four patients. The remaining patients formed a population with a significant linear correlation between ΔCOP and ΔPRA (r=0.56, p<0.01). The slope of the regression line did not differ significantly from the slope of the corresponding line, obtained from postural experiments in normal subjects. Hence, the group of patients with renovascular hypertension had either an exaggerated or a normal postural PRA response. In the majority of patients PRA had increased already after 5 min in the standing position, in contrast to the findings in normal subjects. In half of the patients PRA levels reached a plateau in the standing position, while in the other half a peak value was attained on standing. Eleven patients were cured or improved by surgery. No correlation was found between surgical success and any of the different postural reaction patterns. The paired values for PRA and ASR fitted in with the general correlation between these values in normal subjects and some other hypertensive states.