Pseudohypoaldosteronism without nephropathy masking salt-wasting congenital adrenal hyperplasia genetically confirmed.

Salt-losing crisis with hypoglycaemia and shock are the main manifestations of congenital adrenal hyperplasia (CAH) during the first weeks of life, while hyponatremia and hyperpotassemia alone are seen on mineralocorticoid deficiency or resistance. During the neonatal period, high blood levels of adrenal steroids may lead to confusing laboratory tests not being able to identify the real level of each hormone. A 33-day-old male baby was admitted at the emergency department with severe salt-losing crisis (Na(+) 99 mEq/l and K(+) 9.4 mEq/l) and mild acidosis. No hypoglycaemia or hypotension was seen. Urinary tract infection was excluded. Despite treatment with hydrocortisone and fludrocortisone, hyperpotassemia was hard to control. Laboratory tests could not differentiate between pseudohypoaldosteronism and CAH as both the aldosterone (2454 pg/ml) and 17-OH-progesterone (656.6 ng/ml) levels were high. Diagnosis was made, thanks to the genetic study that proved classical mutations in both alleles of the 21-hydroxylase gene.