A Rare Cause of Hyperkalemia in Neonatal Period: Primary Pseudohypopaldosteronism. Case Report

Background: Pseudohypoaldosteronism (PHA) Type 1 is a rare condition characterized by mineralocorticoid resistance. Despite high levels of aldosterone and plasma renin activity, disease is manifested by salt loss, hypotension, hyperkalemia, hyponatremia and metabolic acidosis.

Case: A 11-day-old newborn was admitted to hospital with complaints of feeding difficulty, weakness and vomiting. He was born to a 32-year-old mother from her fifth pregnancy, as being the third live birth with C/S at gestational age of 38 weeks having a birth weight of 3040 gr. On physical examination his body weight was 2600 g, turgor-tonus were decreased and he was hypoactive. Complete blood count, C-reactive protein and urinalysis values were normal, but he had hyponatremia(Na: 119 meq/L), hyperkalemia(K: 8,8 meq/L) and metabolic acidosis(ph: 7.20, HCO3: 14 mEq/L, BE: -12). Blood samples were taken and hydrocortisone (75 mg/m2/day) and intravenous fluid treatment were given. ACTH, Cortisol and 17-OH progesterone levels were normal. Plasma Renin Activity was 46 ng/ml/h(N: 2-35) and aldesterone level was 835 pg/ml(N: 5-180). Primary PHA was considered according to these results. Urinary system ultrasound was reported as normal. Hydrocortisone treatment was discontinued, but in the follow-up, fludrocortisone was given because of hyperkalemia. He was discharged on postnatal 36th day having a weight of 3675 gr. The clinical spectrum of PHA ranges from asymptomatic patients diagnosed with high renin and aldosterone to patients presenting with a salt-losing crisis. More than 50 different mutations have been identified, but there is no genotype/phenotype correlation. Patients typically present with electrolyte findings that mimic the adrenal crisis. Hyponatremia, hyperkalemia and electrolyte abnormalities of metabolic acidosis are similar in congenital adrenal hyperplasia (CAD) and PHA. However, serum cortisol and aldosterone levels are elevated in PHA. A newborn with hyponatremia, hyperkalemia, metabolic acidosis, dehydration, shock, and feeding difficulty should consider the possibility of PHA with congenital adrenal hyperplasia.