Transcutaneous bilirubin level to predict hyperbilirubinemia in preterm neonates

Background: Hyperbilirubinemia commonly occurs in neonates, with a higher prevalence among preterm neonates, which can lead to severe hyperbilirubinemia. Assessment of total serum bilirubin (TSB) and the use of transcutaneous bilirubinometry (TcB) are existing methods which can identify and predict hyperbilirubinemia. This study aimed to determine TcB cut-off values during the first day for preterm neonates, in order to predict hyperbilirubinemia at 48 and 72 hours. Methods: This cohort study was conducted at Dr. Soetomo General Hospital from September 2018 to January 2019, studying a total of 90 neonates born at ≤35 weeks. They were divided into two groups (Group I: 1000-1500 grams; Group II: 1501-2000 grams). The bilirubin levels were measured at the sternum, using TcB at the ages of 12, 24, and 72 hours. TSB measurements were taken on the third day or if the TcB level reached phototherapy threshold ± 1.24 mg/dL and if TcB showed abnormal results (Group I: 5.76-8.24 mg/dL; Group II: 8.76-11.24 mg/dL). Hyperbilirubinemia was defined as TSB ≥7 mg/dL for Group I and >10 mg/dL for Group II. Results: In total, 38 Group I neonates and 48 Group II neonates were observed. Approximately onehalf of the neonates in Group I (45%) suffered from hyperbilirubinemia at 48 hours, along with 46% of Group II at 72 hours. The best 24-hour-old TcB cut-off values to predict hyperbilirubinemia at 48 hours were calculated to be 4.5 mg/dL for Group I and 5.8 mg/dL for Group II. The determined 24-hour-old TcB value to predict hyperbilirubinemia at 72 hours was 5.15 mg/dL for Group II. Conclusion: TcB values on the first day of life can be used as hyperbilirubinemia predictors on the following days for preterm neonates. Close monitoring should be managed for those with TcB values higher than the calculated cut-off values.