Skin Bilirubin Measurement during Phototherapy in Preterm Jaundice Infants
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Abstract
Objective: To evaluate the correlation between skin bilirubin (transcutaneous bilirubin: TcB) and total serum bilirubin (TSB) levels in preterm jaundice infants during phototherapy.
Methods: Levels of TcB and TSB during phototherapy were measured in preterm jaundice neonates who required phototherapy during September 2011, 1st to July 2012, 31st in Charoenkrung Pracharak Hospital. The TcB was measured over the unexposed (TcBUE) skin underneath the eye pad (glabella region) and exposed skin (TcBE) of the forehead. Pearson’s correlation coefficients were determined. Factors possibly influencing TSB, including TcBUE and TcBE, were analysed with a stepwise multiple linear regression analysis. Factors with significant correlation with TSB were entered into the equation to obtain the predicted TSBs. The predicted TSBs derived from TcBUE and from TcBE were then compared with the actual TSB.
Results: Sixty preterm infants were involved in this study. We found strong correlation between TcBUE - TSB (r=0.73; p-value < 0.001) and TcBE - TSB (r=0.71; p-value < 0.001). Factors which impacted the predicted TSB from TcB during phototherapy were birth weight. The predicted TSB from multiple regression analysis using TcBUE = 0.363 + (0.002 birth weight) + (0.501 TcBUE). While the predicted TSB using TcBE = - 4.230 + (0.005 birth weight) + (1.176 TcBE) - 0.367 (birth weight × TcBE). Defining a difference of ± 1.5 mg/dl as similar, we found that the predicted TSB from TcBUE was similar to the actual TSB in 53.3% and underestimated in 41.7%. The corresponding comparison of the predicted TSB from TcBE to TSB demonstrated 66.7% were similar and 25.0% were underestimated.
Conclusion: Skin bilirubin (TcB) in preterm jaundice infants showed strong correlation with TSB. However, the TcB cannot predict TSB during phototherapy well. Underestimation rate of the predicted TSB during phototherapy was found in high percentage. It is not safe to replace TSB with the TcB, both in exposed and unexposed areas, for a clinical care of preterm infants because it may lead to earlier termination of phototherapy.