Association between early hyponatremia and neurological diagnoses in infants with perinatal asphyxia.

UNLABELLED: To investigate the association between early hyponatremia and long-term neurodevelopmental diagnoses in infants with perinatal asphyxia. This retrospective study included infants born at ≥ 36 weeks of gestation with an ICD-10 diagnosis of perinatal asphyxia and/or hypoxic-ischemic encephalopathy. Data on sodium levels within the first 72 h of life, early postnatal weight change, and clinical follow-up were extracted from medical records. The outcome was death or any ICD-10 diagnoses indicating a neurodevelopmental disorder (NDD), including epileptic, paralytic, hearing, visual and psychiatric/developmental disorders. For multivariable analysis, estimates were adjusted for sex, mode of delivery, and therapeutic hypothermia. Among 269 neonates, 193 (71.7%) had at least one sodium value < 135 mmol/l, 71 (26.4%) < 130 mmol/l and 12 (4.5%) < 125 mmol/l during the first 72 h of life. The median follow-up time was 11.2 years (range 2.4 - 14.8). NDD or death occurred in 57 infants (21.2%). In multivariable analyses, sodium < 125 mmol/l was significantly associated with NDD or death (aOR = 3.85, 95% Cl 1.04-14.22). Sodium < 130 mmol/l was significantly associated with cerebral palsy (aOR = 8.94, 95% Cl 2.24-35.67), epilepsy (aOR = 20.75, 95% Cl 2.39-180.23) and hearing disorders (aOR = 6.09, 95% CI 1.32-28.18). CONCLUSIONS: Our study shows that hyponatremia during the first 72 h of life in infants with perinatal asphyxia is associated with an increased risk of later neurodevelopmental disorders. It remains unclear whether hyponatremia contributes causally to adverse outcomes or primarily serves as a biomarker of severe injury. WHAT IS KNOWN: • Perinatal asphyxia may lead to long-term neurodevelopmental disorders, including cognitive impairment, epilepsy, cerebral palsy, and sensory impairments. • Hyponatremia is common in infants with birth asphyxia and has been associated with low Apgar scores and the severity of hypoxic-ischemic encephalopathy. WHAT IS NEW: • In this study, ICD-10 diagnoses of neurological disorders following perinatal asphyxia were examined using an extended follow-up period. • Early hyponatremia was significantly associated with cerebral palsy, epilepsy and hearing disorders.