Newborns' Low Sodium Tied to Later Brain Disorders or Death

TOPLINEAmong infants with perinatal asphyxia and/or hypoxic-ischaemic encephalopathy (HIE), hyponatraemia during the first 72 hours of life was associated with higher odds of death or later neurodevelopmental disorders (NDDs), particularly cerebral palsy, epilepsy, and hearing disorders.METHODOLOGYResearchers conducted a retrospective cohort study to evaluate the association between early hyponatraemia and long-term neurodevelopmental outcomes in infants with perinatal asphyxia.They included 269 infants (median gestational age, 40.3 weeks; mean birth weight, 3575 g; 58.0% boys) born at 36 weeks of gestation or later and admitted to the NICU in Finland for perinatal asphyxia or HIE between January 2010 and June 2022. The median follow-up duration was 11.2 years.All sodium measurements during the first 72 hours of life were obtained from electronic medical records. Hyponatraemia was defined as a sodium concentration below 135 mmol/L, with additional analyses performed using a sodium concentration below 130 mmol/L and below 125 mmol/L.The outcome was any occurrence of death or the diagnosis of an NDD — including epileptic, paralytic, hearing, visual, or psychiatric/developmental disorders — identified using standardised diagnostic codes.TAKEAWAYDuring the first 72 hours of life, 71.7% of infants developed hyponatraemia, 26.4% had sodium concentrations below 130 mmol/L, and 4.5% had sodium concentrations below 125 mmol/L.During follow-up, 1.9% of infants died within the first 2 weeks of life, and 19.3% were diagnosed with at least one NDD.Severe hyponatraemia (sodium concentrations < 125 mmol/L) was associated with approximately fourfold higher odds of NDDs or death (adjusted odds ratio [aOR], 3.85; 95% CI, 1.04-14.22).A sodium concentration below 130 mmol/L was associated with higher odds of cerebral palsy (aOR, 8.94), epilepsy (aOR, 20.75), and hearing disorders (aOR, 6.09), whereas mild hyponatraemia (sodium concentrations < 135 mmol/L) was not significantly associated with NDDs.IN PRACTICE"It remains unclear whether hyponatremia contributes causally to adverse outcomes or primarily serves as a biomarker of severe injury," the authors wrote.SOURCEThis study was led by Niina Viitaharju, University of Turku, Turku, Finland. It was published online on August 11, 2026, in the European Journal of Pediatrics.LIMITATIONSThe duration of follow-up varied considerably across participants, ranging from 2.4 to 14.8 years. The number and timing of sodium measurements differed among infants, preventing the assessment of the duration of hyponatraemia. The study lacked detailed clinical criteria for determining the severity of HIE.DISCLOSURESThe study was supported by the Foundation of Turku University Central Hospital, the Foundation for Pediatric Research (Finland), the South-Western Finnish Foundation of Neonatal Research, and others. The authors declared having no competing interests.This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.