Newborn Bilirubin and Hyperbilirubinemia Flashcards
Physiologic Jaundice
When does typically peak in newborns and when should it typically resolve by?
Peak - DOL #5
Resolve - 1st-2nd week of life
Jaundice Progression
How does jaundice typically spread on physical exam? What bilirubin levels are typically seen at each stage?
- spreads head to toe
Head/Neck - 5 mg/dL
Upper trunk - 10 mg/dL
Lower trunk/Thighs - 15 mg/dL
Arms/Legs - 15 mg/dL
Palms/Soles - > 15 mg/dL
Definition of Conjugated Hyperbilirubinemia
Direct bilirubin > 2.0 mg/dL or >10% of TSB
What is the maximum rate of bilirubin increase for normal infants without hemolytic hyperbilirubinemia?
5 mg/dL/24 hours or 0.2 mg/dL/hr
What is the ideal rate that phototherapy reduces bilirubin levels by?
1-2 mg/dL within 4-6 hours, with further subsequent decline
Clinical jaundice or TSB >5 mg/dL in the first 24 hours of life should be considered what?
PATHOLOGIC
- get work-up to figure out what’s going on!
When are Breast-feeding Jaundice and Breast Milk Jaundice most likely to occur?
Breast-Feeding: < 1 week of life
Breast Milk: > 1 week of life
What is Breast-Feeding Jaundice?
“not enough milk jaundice” - decreased or poor oral intake
- leads to infrequent stools and scanty BMs = inc. enterohepatic circulation of bilirubin
What is Breast Milk Jaundice? When does it peak?
breast milk prevents bilirubin conjugation (B-glucuronidase)
Peak: 2nd-3rd week of life
- transient unless severe unconjugated hyperbilirubinemia
What are normal Direct and Total Bilirubin levels?
Direct: </= 0.3 mg/dL
Total: 0.1-1.2 mg/dL
What is the definition of severe neonatal hyperbilirubinemia?
TSB > 25 mg/dL
What is the definition of extreme neonatal hyperbilirubinemia?
TSB > 30 mg/dL
How many days to fetal red blood cells survive compared to adult red blood cells?
Fetal = 85 days
Adult = 120 days
What is the typical peak for neonatal TSB?
8-14 mg/dL
What enzyme in the liver is responsible for conjugation of bilirubin?
UGT1A1
What is the physiologic reason for neonates having increased enterohepatic circulation of bilirubin?
dec. gut bacteria = dec. conversion of conjugated bilirubin to urobilin
inc. deconjugation of bilirubin by intestinal mucosa = inc. enterohepatic circulation
What is the physiologic reason for neonates having increased enterohepatic circulation of bilirubin?
dec. gut bacteria = dec. conversion of conjugated bilirubin to urobilin
inc. deconjugation of bilirubin by intestinal mucosa = inc. enterohepatic circulation
What is the most common cause of clinically significant unconjugated hyperbilirubinemia?
increased bilirubin production due to hemolytic diseases
At what age of life are bilirubin levels typically measured in a newborn?
within 24-48 hours of life
What is BIND and what does it stand for?
“Bilirubin-Induced Neurologic Dysfunction”
- unbound bilirubin crosses BBB and binds to brain tissue (basal ganglia and brainstem nuclei)
Which two brainstem nuclei are most often involved in bilirubin-induced neurologic dysfunction (BIND)?
Oculomotor and auditory nuclei
What is the chronic form of BIND called and what symptoms are characteristically seen with it?
Kernicterus (severe form of Chronic Bilirubin Encephalopathy or CBE)
- choreoathetoid cerebral palsy (basal ganglia), gaze palsies (oculomotor nuclei), and sensorineural impairment (auditory nuclei)
- also dental enamel hypoplasia
