ESPE Abstracts

Background: Hyponatremia is one of the most common electrolyte disorders in hospitalized children and early diagnosis and management are crucial to prevent morbidity and mortality. Because of the physiological resistance to aldosterone under 3 months of age, the mechanisms leading to hyponatremia are often misunderstood.

Objective and hypotheses: To assess the prevalence of hyponatremia in hospitalized infants younger than 100 days and evaluate the mechanisms leading to water and sodium imbalance.

Method: The database of a large paediatric hospital was searched for hyponatremia occurring in infants younger than 100 days hospitalized in 2012. The charts were analyzed to evaluate the origin, evaluation and management of hyponatremia.

Results: 86 patients (4.3% of hospitalized children younger than 100 days) were included. The median age at identification of hyponatremia was 19.5 days (IQR 9.25–44.75). 77 patients (89.5%) had hospital-acquired hyponatremia. Iatrogenic mechanisms were involved in 25 cases (29%). The cause of hyponatremia was SIADH in 12 patients (14%), transient or constitutional abnormality of the mineralocorticoid pathway in 28 patients (32.6%), digestive origin in three patients (3.5%), acute renal failure in three patients (3.5%) and heart failure in one patient (1.2%). Abnormality of the mineralocorticoid pathway included functional tubulopathy of prematurity (20 patients; 23.3%), physiological resistance to aldosterone compounded by a severe sepsis (one patient), pseudohypoaldosteronism secondary to pyelonephritis or uropathy (four patients; 4.7%) and constitutional genetic deficiency in the mineralocorticoid pathway (three patients). In 24 patients (27.9%) the etiology of hyponatremia was considered as multifactorial, including iatrogeny (11 patients; 12.7%).

Conclusion: Hyponatremia is a frequent electrolyte disorder in the neonatal pediatric population. Iatrogenic causes played a major role in the occurrence of hyponatremia. Genetic abnormalities of the mineralocorticoid pathway, considered as extremely rare were relatively prevalent and might be otherwise underdiagnosed. We conclude that hyponatremia in infants should be thoroughly analyzed and managed.