RENAL FUNCTION IN PRIMARY ALDOSTERONISM 1

Abstract

Preoperatively, 3 patients with primary aldosteronism showed decreased rates of renal plasma flow, but normal rates of glomerular filtration with increased renal vascular resistance in the 2nd patient, and probably also in the 3rd patient. Maximal nonprotein urinary specific gravity was disproportionately low in relation to other excretory renal functions, and during mannitol osmotic diuresis, the osmolal U/P ratios approximated unity with small net free water clearance in 2 patients. Serum K was low and CO2 combining power increased, but the urinary pH was consistently 7 or more. During osmotic diuresis, the patients excreted large amounts of Na, and also showed high rates of relative K clearance. One patient responded to intravenous acetazoleamide by further decreasing Na reabsorption and increasing K excretion. Urine contained excess protein and white cells. Postoperatively, the renal plasma flow and filtration rate decreased in 2 of the 3 patients and only slowly recovered. Maximal specific gravity remained low, with some tendency to recover, but the capacity to re-absorb water during osmotic diuresis was promptly restored. Patients developed acidosis and normal or somewhat increased serum K concentration and the urine became acid. The defect in Na reabsorption persisted, but the rates of K clearance were greatly decreased. Proteinuria and pyuria subsided completely in 2 of the 3 patients.