Hyponatremia as the cause of seizures in infants: a retrospective analysis of incidence, severity, and clinical predictors

Ann Emerg Med. 1995 Jul;26(1):42-8. doi: 10.1016/s0196-0644(95)70236-9.


Study objectives: (1) To determine the incidence of hyponatremic seizures in infants, (2) to compare the severity and outcome of seizures in hyponatremic and normonatremic patients, and (3) to evaluate the utility of clinical predictors of hyponatremia.

Design: Retrospective chart review of infants who presented to an urban pediatric emergency department from 1988 through 1993.

Participants: Patients who experienced seizures while in the ED. These patients were divided into hyponatremic and normonatremic groups.

Results: Hyponatremia was the cause of seizures in 70% of 47 infants younger than 6 months who lacked other findings suggesting a cause. Median seizure duration was longer in hyponatremic patients (30 versus 17 minutes; P = .007), with a greater incidence of status epilepticus (73% versus 36%; P = .02) and fewer patients with seizures lasting less than 10 minutes (9% versus 36%; P = .04). Emergency intubation was performed more often in hyponatremic patients (12% versus 0%; P = .009). The median temperature was lower in hyponatremic infants than in normonatremic patients (35.5 degrees C versus 37.2 degrees C; P = .0001). Exact logistic-regression methods identified temperature of 36.5 degrees C or less as the best predictor of hyponatremic seizures, with an OR of 64 (95% CI, 8 to 1,026).

Conclusion: Hyponatremia should be strongly suspected in an infant less than 6 months old with seizures and a temperature of 36.5 degrees C or less.

MeSH terms

  • Age Factors
  • Body Temperature
  • Female
  • Humans
  • Hyponatremia / complications*
  • Hyponatremia / diagnosis
  • Hyponatremia / epidemiology
  • Incidence
  • Infant
  • Male
  • Retrospective Studies
  • Seizures / classification
  • Seizures / etiology*
  • Severity of Illness Index
  • Water Intoxication / complications