Unconjugated Hyperbilirubinaemia and Its Effect on Neonatal Distortion Product Otoacoustic Emission and Auditory Brainstem Response- An Observational Study

Abstract AIM To evaluate the association between neonatal hyperbilirubinemia, particularly elevated unconjugated bilirubin, and early hearing dysfunction using Distortion Product Otoacoustic Emissions (DPOAE) and Auditory Brainstem Response (ABR). MATERIALS AND METHODS A prospective study of 2-year duration at a tertiary care centre was performed wherein hyperbilirubinaemic neonates were cases and controls had normal bilirubin levels. Groups 1 and 2 had cases with total bilirubin levels below and above the average (5.17mg/dl) while Groups 3 and 4 included cases with unconjugated bilirubin levels below and above the average (4.18 mg/dl) respectively. All neonates underwent DPOAE on day 3 of life. ABR and repeat DPOAE were done on 30th day of life. Neonates with abnormal ABR were followed up at 3rd and 12th month, with repeat ABR. RESULTS 30th day ABR responses between Group 3 and Group 4 showed statistical significance for the right and left ear (p = 0.037, 0.007), respectively. Repeat DPOAE on day 30 was significant between preterm and term neonates (p = 0.047). There was no association noted between hyperbilirubinaemia and birthweight or gestational age. DPOAE responses showed no statistical significance between cases and controls or any specific DPOAE frequency. All cases of hearing loss were transient and resolved within the first year of life. CONCLUSION Unconjugated hyperbilirubinemia poses a notable risk for early auditory dysfunction, even in the absence of kernicterus. DPOAE and serial ABR are valuable tools for early detection and monitoring. Neonates with elevated unconjugated bilirubin should be prioritized for repeated audiological assessments. Early identification and timely intervention can prevent long-term speech and language delays and improve developmental outcomes.