Neonatal jaundice
Jaundice is common in newborns, but its timing, bilirubin fraction, rate of rise and effect on the baby distinguish physiological jaundice from haemolysis, sepsis, cholestatic liver disease and bilirubin neurotoxicity.
Definition
Neonatal jaundice is visible yellow discolouration caused by raised bilirubin in the first 28 days of life. It is often physiological, but significant unconjugated hyperbilirubinaemia can cause bilirubin encephalopathy, while conjugated jaundice may indicate serious hepatobiliary disease.
First principles
The newborn makes more bilirubin and clears it less efficiently
A newborn has a relatively high red-cell mass and short red-cell lifespan, increasing bilirubin production. Hepatic conjugation and excretion are immature, so a well baby may develop predominantly unconjugated jaundice after the first day. This explanation is only safe after the timing, clinical state and bilirubin measurement have been assessed; visible jaundice alone cannot quantify severity.
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