FAMILIAR HYPERKALEMIC ACIDOSIS

  • 1 January 1985
    • journal article
    • research article
    • Vol. 54  (214) , 161-176
Abstract
A 26-yr-old man with hyperkalemic acidosis, apparently inherited as an autosomal dominant trait, was evaluated. Type II pseudohypoaldosteronism was suggested by normal aldosterone production and renal sodium conservation. The cause of acidosis in this syndrome was unknown. Both urinary ammonium excretion and bicarbonate threshold were low during hyperkalemia. After correcting the hyperkalemia ammonium excretion was normal, but bicarbonate threshold remained low. Maximum bicarbonate reabsorption, urine to blood pCO2 gradients, and minimum urine pH were normal. Hyperkalemia might contribute to the acidosis by limiting buffer, but the primary defect was reduced mineralocorticoid effect on H ion secretion. When the poorly reabsorbed anion, sulfate, was infused, H ion and K secretion were normal. When the relatively reabsorbable anion, chloride, was infused, K secretion was decreased. The attenuated mineralocorticoid effect on hydrogen ion secretion is due to increased reabsorptive avidity for chloride in the distal nephron. To determine if this defect caused resistance to mineralocortocoid, mineralocorticoid was increased by dietary sodium restriction and later desoxycorticosterone and fludrocortisone were administered. Both endogenous and exogenous mineralocorticoid caused increased net acid excretion and corrected the acidosis, indicating no resistance to mineralocorticoid. Hydrochlorothiazide 50 mg daily promptly corrected the acidosis and the hyperkalemia by increased urinary K excretion. The acidosis of type II pseudohypoaldosteronism is due in part to attenuation of the voltage-dependent moiety of mineralocorticoid-driven acificiation caused by enhanced distal chloride reabsorption. Suppression of ammoniagenesis by hyperkalemia exaggerates the acidosis. The acidosis and hyperkalemia are corrected by hydrochlorothiazide.

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