Renal acidosis and renal potassium handling in selective hypoaldosteronism

Selective hypoaldosteronism was demonstrated in a 60 year old black man with moderate renal insufficiency and hyperkalemic, hyperchloremic acidosis. Urine pH was appropriately low during acid loading demonstrating that the hydrogen ion gradient generating capability of the distal-most nephron was intact. In addition to impaired net acid excretion during acidosis, significant bicarbonaturia was present when serum bicarbonate concentration was normal. Desoxycorticosterone acetate (DOCA) administration improved renal potassium handling and corrected the hyperkalemia but not the acidosis or bicarbonaturia. It is concluded that the patient had idiopathic selective hypoaldosteronism and hyporeninemia and that the hyperkalemia was related to hypoaldosteronism. The patient's bicarbonaturia, however, did not appear to be related to mineralocorticoid deficiency and therefore should be attributed to other factors.