Automated Total and Neonatal Bilirubin Values in Newborns: Is a Distinction Clinically Relevant?

Guidelines for managing hyperbilirubinemia in newborns were developed by using diazo methods that measure total and direct-reacting bilirubins and calculate an indirect fraction. The automated Kodak Ektachem system allows for measuring serum bilirubin by either of two dry-slide methods: TBIL, involving a modified diazo method, and NBIL, involving a dual-wavelength colorimetric method that fractionates and directly measures the unconjugated (Bu) and conjugated (Bc) bilirubins (Bu+Bc = neonatal bilirubin). The manufacturer recommends that NBIL be used in newborns less than 15 days old, which is impractical in a large, busy hospital laboratory. We compared NBIL and TBIL in 500 paired serum samples from infants less than 15 days old. We noted a statistically significant difference between TBIL and NBIL values (162.9, SD 70.4, vs 164.6, SD 69.2, mumol/L; P less than 0.0001), which was small and of no clinical significance. We conclude that TBIL values may be used with caution for newborn bilirubin screening. Furthermore, NBIL measurements are an acceptable alternative to diazo measurements for neonatal care, allowing the use of previously developed guidelines with NBIL values.

Comparison of arterial and capillary bilirubin values in neonates with arterial lines

To determine whether arterial and capillary values for bilirubin agree in neonates, we analyzed 35 simultaneously sampled capillary and arterial specimens from 13 infants. We found a high correlation between arterial and capillary bilirubin values (r = 0.993). We conclude that arterial bilirubin samples may be substituted for capillary samples in newborn infants.

Automated total and neonatal bilirubin values in newborns: is a distinction clinically relevant?

Guidelines for managing hyperbilirubinemia in newborns were developed by using diazo methods that measure total and direct-reacting bilirubins and calculate an indirect fraction. The automated Kodak Ektachem system allows for measuring serum bilirubin by either of two dry-slide methods: TBIL, involving a modified diazo method, and NBIL, involving a dual-wavelength colorimetric method that fractionates and directly measures the unconjugated (Bu) and conjugated (Bc) bilirubins (Bu+Bc = neonatal bilirubin). The manufacturer recommends that NBIL be used in newborns less than 15 days old, which is impractical in a large, busy hospital laboratory. We compared NBIL and TBIL in 500 paired serum samples from infants less than 15 days old. We noted a statistically significant difference between TBIL and NBIL values (162.9, SD 70.4, vs 164.6, SD 69.2, mumol/L; P less than 0.0001), which was small and of no clinical significance. We conclude that TBIL values may be used with caution for newborn bilirubin screening. Furthermore, NBIL measurements are an acceptable alternative to diazo measurements for neonatal care, allowing the use of previously developed guidelines with NBIL values.