Pseudohypoaldosteronism: mineralocorticoid unresponsiveness syndrome.

We described a 10 day old boy who presented with hyponatremia, hyperkalemia, and metabolic acidosis. Therapeutic treatment with exogenous glucocorticoid and mineralocorticoid for 8 months failed to correct the electrolyte abnormalities. The elevated serum cortisol up to 44.34 micrograms/dl along with the absence of skin hyperpigmentation excluded defects in the glucocorticoid pathway. Pseudohypoaldosteronism was diagnosed on the basis of hyponatremia, severe urinary salt loss despite the markedly elevated serum aldosterone up to 6,500 pg/ml (normal range 50-800 pg/ml). The patient responded very well to oral salt supplementation and cation exchange resin therapy shown by normal physical growth and normal levels of serum electrolytes.