Incidence of suppressed renin activity and of normokalemic primary aldosteronism in hypertensive Negro patients

In 35 normokalemic Negro patients with benign essential hypertension, plasma renin activity (PRA) was measured by the method of Boucher and associates, while they were on regular diets, after ambulation, sodium restriction and thiazide medication, and again after rigid sodium depletion in the hospital. In nine (26%) inadequate PRA response was elicited even after the latter regimen. In only two of these (6%) was elevated excretion of aldosterone demonstrated. Suppressed PRA is commonly encountered in apparent benign essential hypertension and it occurs much more frequently than normokalemic primary aldosteronism does. Casual measurement of PRA in ambulatory patients is of little differential diagnostic value in primary aldosteronism.