Clinical

Bilirubin level linked to auditory brainstem response in jaundiced newborns

Last Updated: 2008-05-26 10:00:38 -0400 (Reuters Health)

NEW YORK (Reuters Health) - In neonatal jaundice, the risk of an abnormal automated auditory brainstem response (AABR) increases as the unbound, but not total, bilirubin concentration rises, according to a report in the May issue of Pediatrics.

Hyperbilirubinemia has been shown to affect the AABR, commonly used to evaluate hearing in infants during the first few days of life, and Dr. Charles E. Ahlfors and Anne E. Parker, from the California Pacific Medical Center in San Francisco, sought to clarify the relative impact of total and unbound bilirubin levels on AABR changes.

The study involved 44 jaundiced newborns of at least 34 weeks gestation who underwent AABR testing within 4 hours of total and unbound bilirubin measurement. Overall, 4 infants (9%) did not achieve a passing AABR result and were referred for further evaluation.

Average total bilirubin concentrations in newborns who did and did not pass AABR testing were comparable, at around 22 mg/dL. By contrast, the unbound bilirubin level was significantly higher in infants who did not pass the test: 2.62 vs. 1.32 micrograms/dL.

"Although the total bilirubin concentration has long been ingrained in clinical thinking and practice as the principle metric for determining the likelihood of bilirubin-induced neurotoxicity, it is evident from our data that bilirubin may at times be inappropriately acquitted as the culprit in hearing deficits because the total bilirubin concentration is 'unremarkable'," the authors state.

Pediatrics 2008;121:976-978.