Idiopathic SIADH in the premature newborn, a case report

van der Lee, D.*, de Bruin, C., Steggerda, S.J., Vlaardingerbroek, H. | JNPM 2020;


BACKGROUND: Hyponatremia is a common laboratory finding in premature and ill neonates. When the degree of hyponatremia is more severe, the likelihood of a pathologic entity increases. In this case report we describe a premature neonate with severe hyponatremia due to the idiopathic syndrome of inappropriate antidiuretic hormone secretion (SIADH).

CASE DESCRIPTION: The patient is a male neonate, born prematurely. He was admitted to the neonatal intensive care unit and received non-invasive respiratory support. After 48 hours of life serum sodium (Na+) decreased to 115 mmol/l. Hyponatremia progressively worsened despite aggressive Na+ supplementation. The clinical and laboratory data were most consistent with severe SIADH. Fluid restriction was initiated which resulted in a gradual normalization of Na+. A causal factor for development of SIADH could not be identified.

CONCLUSION: When a neonate presents with significant hyponatremia that is not responsive to conventional therapy, it is important to perform a diagnostic work-up for SIADH, even in the absence of overt triggering factors.

*Corresponding Author: 

D. van der Lee, MD, Department of Pediatrics, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, Netherlands. Tel.: +31630875873; E-mail: