Reversible secondary pseudohypoaldosteronism due to pyelonephritis.

We report a 5-week-old boy who developed severe hyponatremia and hyperkalemia secondary to acute pyelonephritis. The patient presented with non-specific signs, including poor appetite, failure to thrive, and dehydration. An endocrinological evaluation led to a diagnosis of pseudohypoaldosteronism. The patient had phimosis, but no congenital urinary tract malformations. Outflow obstruction secondary to the phimosis appears to have caused pyelonephritis, and renal inflammation decreased responsiveness to aldosterone transiently.