Hyporeninemic hypoaldosteronism in two patients with systemic lupus erythematosus.

Two patients with systemic lupus erythematosus (SLE) and hyperkalemia were studied. The hyperkalemia was disproportionate to the degree of renal excretory impairment. The usual causes of hyperkalemia were excluded. Basal levels of plasma renin activity (PRA) and plasma aldosterone (PAC) were low. The responses of PRA and plasma aldosterone to the combined stimulus of ambulation and furosemide were blunted. Plasma levels of 18-hydroxycorticosterone (18-OH-B) were normal. The hyperkalemia in both patients could be attributed to hyporeninemic hypoaldosteronism (HH). In one patient, the hyperkalemia was corrected by the administration of fludrocortisone. In the second patient, treatment of lupus nephritis with azathioprine, prednisone, and plasmapheresis normalized both the serum creatinine and the serum potassium.