Correlation of the transcutaneous bilirubin and serum bilirubin levels measured before and after phototherapy in newborns: a prospective observational study

Aim: The purpose of the present study was to show the reliability of the transcutaneous bilirubin (TcB) measurement as an alternative method to total serum bilirubin (TSB) when starting treatment with phototherapy (PT), which is one of the most important treatment methods of hyperbilirubinemia as a very common practice in the neonatal period and eliminates the disadvantages of blood collection. Materyal and Method: Two measurements were made to evaluate whether there was a correlation between the total serum bilirubin and transcutaneous bilirubin level measurement for follow-up in newborns who were hospitalized and prospectively followed up in the Newborn Intensive Care Unit of Karabuk University Medical Faculty Training and Research Hospital between April 13 and June 30, 2022 (Level III Neonatal Center) who were scheduled for starting phototherapy. The primary result was the correlation between TcB and TSB at the first 24 hours and after, at the initiation of FT, termination of FT, and 12 hours after PT was discontinued. Results: The TSB and TcB values of the newborns ​​were measured at the beginning of PT, at the end of PT, and 12 hours after PT was ended. The first measurement values ​​were 11.60±5.16 and 10.72±4.02, respectively; the second measurement values ​​were 7.45±2.34 and 6.35±2.83, respectively; and the third measurement values ​​were 8.03±2.45 and 7.35±2.63 mg/dL, respectively. A strong positive correlation was found among all measurement values. Also, when the newborns who received FT for the first 24 hours were evaluated by subgrouping, the high correlation between TcB and TSB levels continued. Conclusion: The present study showed that there is a significant relationship between TcB taken from the covered skin and TSB at the start, end, and 12 hours after PT. Also, when the newborns who received PT for the first 24 hours were evaluated in a subgroup, it was found that TCB measurement predicted the TSB level at a high level before and after PT. Based on these findings, it was concluded that TcB measurement, including in the first 24 hours, is reliable in the follow-up of newborns receiving PT for the treatment of hyperbilirubinemia. However, we think that larger prospective controlled studies are required in this respect.