Correlation between Transcutaneous Bilirubin (TCB) and Total Serum Bilirubin (TSB) in Term Neonates Prior to Phototherapy: A CrossSectional Study

Background: Accurate assessment of neonatal hyperbilirubinemia is crucial to prevent bilirubin-inducedneurological dysfunction. Total serum bilirubin (TSB) estimation remains the diagnostic gold standard, whiletranscutaneous bilirubin (TCB) measurement provides a rapid, non-invasive alternative. This study aimed toevaluate the correlation between TCB and TSB values measured prior to initiation of phototherapy in termneonates.Methods: This cross-sectional analysis included 100 term neonates enrolled in a randomized controlled trialconducted at a tertiary care hospital in Rajasthan. Prior to initiation of phototherapy, TCB was measured using atranscutaneous bilirubinometer, followed immediately by venous sampling for TSB estimation using anautomated analyzer (Erba Mannheim XL-640/EM 360). Descriptive statistics and Pearson correlationcoefficient were used to assess the relationship between TCB and TSB values.Results: The mean TCB level was 18.85 ± 1.90 mg/dL, while the mean TSB level was 18.87 ± 1.95 mg/dL,showing a negligible mean difference of 0.02 mg/dL. However, the Pearson correlation coefficient betweenTCB and TSB was r = 0.35, indicating a moderate positive correlation. Increasing variability between TCB andTSB measurements was observed at higher bilirubin levels (>18 mg/dL).Conclusion: Although mean TCB values closely approximated mean TSB levels, the moderate correlationsuggests that TCB alone is insufficient for precise individual-level clinical decision-making. TCB is a usefulscreening tool to identify neonates requiring further evaluation; however, confirmatory TSB estimation remainsessential before initiating treatment, particularly at higher bilirubin levels.