The objective of this study was to evaluate the correlation and agreement between transcutaneous and serum bilirubin among preterm low-birth-weight neonates. Neonates born at <35 weeks of gestation with birth weight <2,000 g were enrolled prospectively. Transcutaneous bilirubin (TcB) was measured at forehead, sternum, and abdomen at 24 ± 6 and 72 ± 12 h after birth and when icterus involved arms or legs (Kramer zone 4-5). Serum total bilirubin (STB) was measured by microbilimeter (STB-M) at all these time-points and by high-performance liquid chromatography (STB-H) at one randomly chosen time-point. A total of 1,619 observations were made in 256 neonates (median gestation, 34 weeks (IQR, 32-35), birth weight 1,522 ± 288 g). Overall there was excellent correlation and agreement between TcB and STB-M with TcB on forehead being most accurate (r = 0.84, mean difference, 0.3 ± 1.9 mg/dL) followed by TcB on abdomen (r = 0.73, mean difference, 1.5 ± 2.6 mg/dL) and sternum (r = 0.72, mean difference, 1.5 ± 2.6 mg/dL). TcB performed well at all three points of measurement with best correlations being observed at icterus level 4/5. Correlation between TcB and STB-H measured by high-performance liquid chromatography was less strong but significant (r = 0.59 to 0.69 at different time points of measurement).
Conclusions: TcB has good correlation and agreement with STB in preterm low-birth-weight neonates born at ≥28 weeks of gestation.