Editing Jaundice (section)

==== Pathophysiology ====
Transient [[neonatal jaundice]] is one of the most common conditions occurring in newborns (children under 28 days of age) with more than 80 per cent experienceing jaundice during their first week of life.<ref>{{cite journal | vauthors = Maisels MJ | title = Managing the jaundiced newborn: a persistent challenge | journal = CMAJ | volume = 187 | issue = 5 | pages = 335–343 | date = March 2015 | pmid = 25384650 | pmc = 4361106 | doi = 10.1503/cmaj.122117 }}</ref> Jaundice in infants, as in adults, is characterized by increased bilirubin levels (infants: total serum bilirubin greater than 5&nbsp;mg/dL).{{cn|date=March 2025}}

Normal physiological neonatal jaundice is due to immaturity of liver enzymes involved in bilirubin metabolism, immature gut microbiota, and increased breakdown of fetal hemoglobin (HbF).<ref>{{cite book|title=Oxford Handbook of Clinical Specialties|vauthors=Collier J, Longore M, Turmezei T, Mafi AR|publisher=Oxford University Press|year=2010|isbn=978-0-19-922888-1|chapter=Neonatal jaundice}}{{page needed|date=July 2015}}</ref> Breast milk jaundice is caused by an increased concentration of [[β-glucuronidase]] in breast milk, which increases bilirubin deconjugation and reabsorption of bilirubin, leading to persistence of physiologic jaundice with unconjugated hyperbilirubinemia. Onset of breast milk jaundice is within 2 weeks after birth and lasts for 4–13 weeks.{{cn|date=May 2022}}

While most cases of newborn jaundice are not harmful, when bilirubin levels are very high, brain damage—[[kernicterus]]—may occur<ref>{{cite web|date=February 23, 2015|title=Facts about Jaundice and Kernicterus|url=https://www.cdc.gov/ncbddd/jaundice/facts.html|url-status=live|archive-url=https://web.archive.org/web/20160808204002/http://www.cdc.gov/ncbddd/jaundice/facts.html|archive-date=8 August 2016|access-date=13 August 2016|website=CDC}}</ref><ref name="Kap2017" /> leading to significant disability.<ref name="family">{{cite journal|vauthors=Click R, Dahl-Smith J, Fowler L, DuBose J, Deneau-Saxton M, Herbert J|year=2013|title=An osteopathic approach to reduction of readmissions for neonatal jaundice|journal=Osteopathic Family Physician|volume=5|issue=1|pages=17–23|doi=10.1016/j.osfp.2012.09.005}}</ref> Kernicterus is associated with increased unconjugated bilirubin (bilirubin which is not carried by [[albumin]]). Newborns are especially vulnerable to this damage, due to increased permeability of the [[blood–brain barrier]] occurring with increased unconjugated bilirubin, simultaneous to the breakdown of fetal hemoglobin and the immaturity of gut flora. This condition has been rising in recent years, as babies spend less time in sunlight.{{Citation needed|date=June 2020}}