Pseudohypoaldosteronism due to Sweat Gland Dysfunction

Abstract

Extract: Pseudohypoaldosteronism is an uncommon disorder characterized by urinary sodium wasting and is attributed to a defect in distal renal tubular sodium handling with failure to respond to endogenous aldosterone. Sweat electrolyte values in other reported patients, when measured, have been normal. A 3.5-year-old girl developed repeated episodes of dehydration, hyponatremia, and hyperkalemia during the first 19 months of life. Serum sodium was as low as 113 mEq/liter and potassium as high as 11.1 mEq/liter. Her plasma and urinary aldosterone levels were persistently elevated (Figs. 1–4). Unlike patients with classic pseudohypoaldosteronism she demonstrated no urinary sodium wasting (Figs. 2 and 3). During episodes of hyponatremia and reduced sodium intake her urinary sodium was less than 5 mEq/liter. In addition, her sweat sodium concentration was consistently above 125 mEq/liter and salivary sodium concentration above 58 mEq/liter. Her chest x-ray, 72-hr fecal fat excretion, serum and urinary pancreatic amylase (amy-2) were normal, providing no evidence for cystic fibrosis. It is proposed that this patient represents a new variant of pseudohypoaldosteronism with excessive loss of sodium from the sweat and salivary glands instead of the kidneys. Spectulation: Aldosterone is known to control sodium and potassium excretion by kidneys, sweat glands, and salivary glands. In patients with classic pseudohypoaldosteronism there is a defect in renal tubular response to aldosterone action. Studies in the present patient suggest that there may be variants of this syndrome in which the end organ defect is in the sweat and salivary glands instead of the renal tubule. In addition, it is possible that new variants will be found in which end organ defect is in still other organs concerned with electrolyte transport.