Sodium of 106 in a 2-week-Old: An electrolyte crisis without a diagnosis

Abstract

Background

Neonatal electrolyte crises are rare yet potentially fatal. Hyponatremia in the neonatal population is associated with significant morbidity and mortality, with symptoms including vomiting, lethargy, seizures, and coma. Hyponatremia can co-occur with other electrolyte abnormalities such as hyperkalemia, which can induce life-threatening cardiac arrhythmias. We present the case of a neonate who appeared clinically stable but was discovered to have profound electrolyte disturbances requiring urgent intervention and extensive diagnostic evaluation.

Case report

A 15-day-old full-term male presented to the pediatric emergency department (ED) with persistent emesis and poor weight gain, weighing 0.78 kg below birthweight. Birth history, newborn screening, and physical exam were unremarkable, though family history included Russell-Silver Syndrome (RSS). Laboratory testing revealed hyponatremia (106 mmol/L), hyperkalemia (6.8 mmol/L), and hypochloremia (75 mmol/L). He was managed with isotonic saline, furosemide, calcium gluconate, albuterol, and magnesium sulfate. The patient was admitted to the intensive care unit, where electrolytes stabilized over an 11-day hospitalization. A comprehensive workup initiated in the ED investigated congenital adrenal hyperplasia (CAH), pseudohypoaldosteronism (PHA), Addison's disease, aldosterone synthase deficiency (ASD), and RSS, though no definitive diagnosis was established.

Why should an emergency physician be aware of this?

Neonates with severe electrolyte abnormalities may appear deceptively well on exam. Subtle signs such as persistent emesis and inadequate weight gain are critical clues. Early recognition and empiric management are imperative, especially as newborn screening may not detect rarer adrenal disorders. Multidisciplinary collaboration between the ED and pediatric subspecialists is essential for timely evaluation and effective treatment.