Background: Hyperbilirubinemia in term newborns needing phototherapy within 48 hours after birth, early-onset hyperbilirubinemia, has not been evaluated in recent Japanese healthy birth centers. In this study, we sought to determine the cause of early-onset hyperbilirubinemia in a Japanese healthy birth center and to evaluate the 1992 Kobe University phototherapy treatment criterion requiring total serum bilirubin (TSB) and unbound bilirubin (UB).
Methods: In this retrospective observational study, we collected data on newborns diagnosed with early-onset hyperbilirubinemia between 2009 and 2016 at the Chibune General Hospital. Causes of the disease were investigated, as well as which index (TSB or UB) was used for treatment decisions.
Results: Overall, 76 term newborns were included in the analysis. Twenty-seven newborns (36%) found the cause (ABO blood type incompatibility [n=17, 22%], polycythemia [n=8, 11%], and cephalohematoma [n=2, 3%]). However, 49 newborns (64%) did not find any causes (i.e., idiopathic hyperbilirubinemia). Of these, 27 observed more than 5% weight loss from birth weight. Seventy (92%) newborns had abnormal TSB only, and 5 (7%) had abnormal TSB and UB values. Only 1 (1%) newborn with only abnormal UB values received phototherapy.
Conclusions: Altogether, data from this Japanese healthy birth center suggest that many apparently healthy newborns with or without excessive weight loss develop early-onset hyperbilirubinemia. In the 1992 Kobe University phototherapy treatment criterion, TSB, not UB, was the main index used to make treatment decisions in these patients.
Keywords: early-onset hyperbilirubinemia; term newborns; total serum bilirubin; unbound bilirubin.