A new Australian kindred with the syndrome of hypertension and hyperkalaemia has dysregulation of atrial natriuretic factor.

A family with the syndrome of hypertension and hyperkalaemia affecting six members in two generations is reported from Australia, where the first two sporadic cases were described. All family members had hyperkalaemia, hyperchloraemia and normal creatinine clearance. Only one affected adult and no affected children were hypertensive, possibly because of habitual low-salt diets. Plasma potassium fell significantly during fludrocortisone acetate administration, and urine potassium increased during saline infusion, consistent with renal tubular responsiveness to mineralocorticoid. Low plasma renin activity and pressor hyper-responsiveness to angiotensin II suggested sodium volume overload, but atrial natriuretic factor (ANF) was normal or only slightly elevated when compared with clearly elevated levels in primary aldosteronism. Plasma ANF was unresponsive to the usually reliable stimulus of angiotensin infusion in the two brothers affected and to saline infusion in one of them. These findings are consistent with a renal tubular avidity for sodium, leading to volume expansion, suppression of renin, and, depending on dietary sodium intake, hypertension. A role for dysregulation of ANF in the pathophysiology is possible.