In plain words
Bilirubin is a yellow substance made when red blood cells break down. Everyone has some, and the liver normally processes it and sends it out in stool. Newborns make more of it than adults, because they have more red blood cells and those cells are recycled quickly. A newborn's liver is still developing, so it can take days to clear the load. When bilirubin builds up in the skin and the whites of the eyes, the baby looks yellow. This is . In most babies the rise is normal and passes within the first weeks. Clinicians measure bilirubin with a skin reading or a blood test and compare the result with thresholds that depend on the baby's age and risk. A high level can affect the brain, which is why it is checked closely.
The deeper version
Unconjugated bilirubin is generated mainly from heme catabolism of senescent red cells and, in neonates, from a larger red-cell mass and shorter red-cell lifespan. Hepatic glucuronidation by UDP-glucuronosyltransferase is immature in the first days of life, and through beta-glucuronidase activity in the gut prolongs exposure. Unconjugated bilirubin that exceeds albumin binding capacity can cross the blood-brain barrier, which underlies the risk of . The AAP's 2022 guideline (Kemper and colleagues, Pediatrics, 2022) sets management by total serum bilirubin relative to gestational age, age in hours, and neurotoxicity risk factors, using and exchange transfusion thresholds from a bilirubin nomogram. Transcutaneous measurement is used for screening, with serum confirmation. Debate continues over optimal thresholds and over routine screening after discharge.
Where it comes up
- Newborn jaundiceBaby Basics
- Feeding a baby with jaundiceFeeding Your Baby
- Is my baby getting enough?Feeding Your Baby
- Diaper counts and what newborn poop looks likeBaby Basics
- Pediatrician visits in the first weeksBaby Basics
What mothers here say about bilirubin
No one has posted under this term yet.
Sources
- Kemper AR and colleagues, American Academy of Pediatrics — Clinical Practice Guideline Revision: Management of Hyperbilirubinemia in the Newborn Infant 35 or More Weeks of Gestation, 2022
- Centers for Disease Control and Prevention — Neonatal jaundice: information for families