Timing, duration, and severity of hyponatremia following pediatric brain tumor surgery*.
OBJECTIVE
To describe the time course, variability, and magnitude of serum sodium changes among children undergoing intracranial tumor surgery.


METHODS
Retrospective cohort study.


METHODS
Tertiary children's hospital in Salt Lake City, UT.


METHODS
Children 0-19 years undergoing first neurosurgical procedure for an intracranial tumor, treated during January 2001 and February 2012.


METHODS
None.


RESULTS
Three hundred nineteen patients were placed in three exclusive groups based on the lowest serum sodium measurement during admission: 1) severe hyponatremia: serum sodium less than or equal to 130 mEq/L; 2) mild hyponatremia: 131-135 mEq/L; and 3) normal sodium: more than 135 mEq/L. Timing and severity of sodium perturbations were assessed within each group. Hundred thirty-seven patients (43%) had mild hyponatremia, 39 (12%) had severe hyponatremia, and 143 (45%) had normal sodium. After surgery, sodium decreased in all groups with lower averaged concentrations during postoperative days 0-1 and 5-6, although patients with severe hyponatremia had the greatest decline. Nearly 80% of hyponatremic patients had mild hyponatremia prior to development of severe hyponatremia; median time between mild hyponatremia and severe hyponatremia was 1.6 days (interquartile range, 0.4-5.6). Seventy-five percent of patients manifest mild hyponatremia within two postoperative days; however, severe hyponatremia developed later with 75% of patients manifesting severe hyponatremia within six postoperative days. Nine patients had initial severe hyponatremia between days 6 and 20 after surgery. Patients with severe hyponatremia had greater sodium variability with significantly lower nadirs, greater maximum values, and larger decreases within 24-hour periods compared with other sodium groups. Seventy-five percent of children with severe hyponatremia spent more than 4 days with abnormally low sodium values. Among hyponatremic patients, obstructive hydrocephalus and age less than 3.5 years were significant independent risk factors for severe hyponatremia.


CONCLUSIONS
Hyponatremia developed in just over half of children. Young children with hydrocephalus have increased risk of severe hyponatremia. Those with severe hyponatremia need frequent and prolonged monitoring because of risk for repeat sodium changes. Further study is needed to evaluate ideal monitoring and treatment of severe hyponatremia after intracranial tumor surgery.
1Department of Pediatrics, University of Utah, Salt Lake City, UT. 2Department of Neurosurgery, University of Utah, Salt Lake City, UT. 3Department of Internal Medicine, Division of Epidemiology, University of Utah, Salt Lake City, UT.
Jennifer S
JS
Belzer
Cydni N
CN
Williams
Jay
J
Riva-Cambrin
Angela P
AP
Presson
Susan L
SL
Bratton
D000367:Age Factors; D001932:Brain Neoplasms / Q000097:blood* / Q000150:complications / Q000601:surgery*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000150:complications; D007010:Hyponatremia / Q000097:blood* / Q000209:etiology; D007223:Infant; D008297:Male; D011183:Postoperative Complications / Q000097:blood* / Q000209:etiology; D012189:Retrospective Studies; D012720:Severity of Illness Index; D012964:Sodium / Q000097:blood; D013997:Time Factors
D012964:Sodium