Familial Hyperpotassemia and Hypertension Accompanied by Normal Plasma Aldosterone Levels

Hypertension and hyperpotassemia that were accompanied by normal plasma aldosterone and low renin levels and were responsive to chlorothiazide administration were found in a 29-year-old patient and two decades later in his 21-year-old son. Their renal function is normal, including response to sodium sulfate, mannitol, and aldosterone infusions. Adrenal insufficiency was excluded. The renin-aldosterone system was proved intact by physiological and pharmacologic stress and angiotensin-II infusion. Also normal were values for blood counts, blood volumes, and erythrocyte and exchangeable body potassium. The postulation of a defective cell membrane impeding potassium influx is supported by the failure of glucose and insulin infusions to substantially reduce hyperpotassemia. In the context of a hereditary disorder (the pedigree, compatible with autosomal dominant inheritance, includes five affected in two generations), hypertension is a second phenotypic character of a single defective pleiotropic gene although its pathogenesis remains unclear.