Measurement of bilirubin (in a neonate)

How to measure the bilirubin level

Use serum bilirubin measurement for babies:

• in the first 24 hours of life or
• who have a gestational age of less than 35 weeks

In babies who have a gestational age of 35 weeks or more and who are over 24 hours old:

• use a transcutaneous bilirubinometer to measure the bilirubin level
• if a transcutaneous bilirubinometer is not available, measure the serum bilirubin
• if a transcutaneous bilirubinometer measurement indicates a bilirubin level greater than 250 micromol/litre, measure the serum bilirubin to check the result
• use serum bilirubin measurement if bilirubin levels are at or above the relevant treatment thresholds for their age, and for all subsequent measurements

Measuring and monitoring bilirubin thresholds before and during phototherapy

Before starting phototherapy

In babies who are clinically well, have a gestational age of 38 weeks or more and are more than 24 hours old, and who have a bilirubin level that is below the phototherapy threshold but within 50 micromol/litre of the threshold (see the threshold table and the treatment threshold graphs), repeat bilirubin measurement as follows:

• within 18 hours for babies with risk factors for neonatal jaundice (those with a sibling who had neonatal jaundice that needed phototherapy or a mother who intends to exclusively breastfeed)
• within 24 hours for babies without risk factors

In babies who are clinically well, have a gestational age of 38 weeks or more and are more than 24 hours old, and who have a bilirubin level that is below the phototherapy threshold by more than 50 micromol/litre (see the threshold table and the treatment threshold graphs), do not routinely repeat bilirubin measurement.

Do not use phototherapy in babies whose bilirubin does not exceed the phototherapy threshold levels in the threshold table and the treatment threshold graphs.

Reference:

• NICE (May 2016). Jaundice in newborn babies under 28 days - update.