Pseudohypoaldosteronism. Clinical, biochemical and morphological studies in a long-term follow-up.

A boy with pseudohypoaldosteronism was followed from birth to the age of 7 years. Failure to thrive, vomiting, dehydration, hyponatraemia and urinary sodium loss were prominent findings. Urinary excretion of corticosteroid metabolites was normal. Before treatment, excessively high plasma renin concentration was found, associated with a marked activation of aldosterone secretion. A renal biopsy showed pronounced hypertrophy of the juxtaglomerular apparatus. Persisting metabolic acidosis and an insufficient urinary acidifying capacity suggested the presence of distal renal tubular acidosis. Treatment with sodium bicarbonate and sodium chloride from 19 to 31 months of age resulted in normal growth and normal physical and mental development. The plasma electrolytes were normalized but a pronounced activation of the renin-aldosterone system persisted after therapy, and on sodium restriction this system responded with a considerable further activation.