STUDIES OF RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM IN PATIENTS WITH HYPERTENSION AND IN NORMAL SUBJECTS

A study was made of the effects of a high sodium (200 mEq.) and a low sodium (10 mEq.) diet and of posture on absolute changes and interrelationships between body weight, plasma volume, plasma renin activity (PRA), aldosterone excretion, sodium excretion and plasma electrolytes in forty-one patients with various types of hypertension and in nine normal subjects. Significant correlations were found in the normal and hypertensive subjects (except the one patient with primary aldosteronism) between successive parameters in the sequence Δbody weight → Δplasma volume→ Δ PRA → Δaldosterone excretion → Δsodium excretion. Thus, the renin-angiotensin-aldosterone system appears to operate in hypertensive subjects as in normal man with the following exceptions: 1. (1) Nineteen patients with essential hypertension showed a significantly subnormal rise in aldosterone excretion in response to the normal rise in plasma renin activity observed on the low sodium diet; nevertheless urine sodium was reduced normally by the low salt diet presumably partly by a nonaldosterone mechanism. 2. (2) Of ten patients with macroscopic or microscopic evidence of renal arterial occlusion(s), nine showed the expected increase in plasma renin activity on the low sodium diet after standing (but only inconsistently in other conditions); and there was significant expansion of the plasma volume on the high sodium diet, excessive aldosterone excretion on both diets, and resistance to the pressor effects of infused angiotensin. The tenth patient had normal plasma renin activity, normal resistance to infused angiotensin and no improvement after successful correction of his undoubted but probably only incidental renal arterial stenosis. 3. (3) Four patients with renal insufficiency had relatively fixed body weights, fixed elevations of plasma volume, normal levels of plasma renin activity, normal aldosterone excretion and normal sensitivity to infused angiotensin. 4. (4) Five patients could not be classified. Aldosterone excretion was excessive in three patients, associated with appropriate levels of plasma renin activity in two and with probably elevated plasma renin activity in one who, at autopsy, had normal or perhaps excessive granulation of the juxtaglomerular apparatus. Two of the unclassified patients, both Negroes, showed abnormally low levels of plasma renin activity, low aldosterone excretion and relatively fixed levels of plasma volume, raising the theoretic possibility of the presence of a deoxycorticosteronesecreting adrenocortical tumor. This possibility was supported by the finding of excessive urinary excretion of deoxycorticosterone in one of the patients. © 1969.