[Low renin variant of hypertension: functional relations of the renin-aldosterone pressor system]

Renin-aldosterone function was studied in 23 patients with low-renin essential hypertension (LREH) under resting and stimulated conditions. Patients were selected on the basis of differential diagnostic tests of renin-angiotensin stimulation and inhibition as well as roentgeno-radiologic findings in order to rule out adrenal lesions. The results were compared with those of patients with primary aldosteronism and with essential hypertension where renin activity can be stimulated under similar sodium balance conditions. Intravenous or prolonged furosemide administration was shown to be the test of choice for the diagnosis of renin suppression. The renin-aldosterone system of LREH patients featured subnormal renin activity and normal aldosterone levels in baseline conditions, and the lack of renin stimulation together with limited aldosterone stimulation following functional tests. The analysis of changes in diuresis, natriuresis and the pattern of Na/K coefficient points to a great diuretic and natriuretic effect of furosemide in patients with LREH.