Newborn Bilirubin and Hyperbilirubinemia

Question 1

Physiologic Jaundice

When does typically peak in newborns and when should it typically resolve by?

Answer 1

Peak - DOL #5

Resolve - 1st-2nd week of life

Question 2

Jaundice Progression

How does jaundice typically spread on physical exam? What bilirubin levels are typically seen at each stage?

Answer 2

• 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

Question 3

Definition of Conjugated Hyperbilirubinemia

Answer 3

Direct bilirubin > 2.0 mg/dL or >10% of TSB

Question 4

What is the maximum rate of bilirubin increase for normal infants without hemolytic hyperbilirubinemia?

Answer 4

5 mg/dL/24 hours or 0.2 mg/dL/hr

Question 5

What is the ideal rate that phototherapy reduces bilirubin levels by?

Answer 5

1-2 mg/dL within 4-6 hours, with further subsequent decline

Question 6

Clinical jaundice or TSB >5 mg/dL in the first 24 hours of life should be considered what?

Answer 6

PATHOLOGIC

• get work-up to figure out what’s going on!

Question 7

When are Breast-feeding Jaundice and Breast Milk Jaundice most likely to occur?

Answer 7

Breast-Feeding: < 1 week of life

Breast Milk: > 1 week of life

Question 8

What is Breast-Feeding Jaundice?

Answer 8

“not enough milk jaundice” - decreased or poor oral intake

• leads to infrequent stools and scanty BMs = inc. enterohepatic circulation of bilirubin

Question 9

What is Breast Milk Jaundice? When does it peak?

Answer 9

breast milk prevents bilirubin conjugation (B-glucuronidase)

Peak: 2nd-3rd week of life

• transient unless severe unconjugated hyperbilirubinemia

Question 10

What are normal Direct and Total Bilirubin levels?

Answer 10

Direct: </= 0.3 mg/dL

Total: 0.1-1.2 mg/dL

Question 11

What is the definition of severe neonatal hyperbilirubinemia?

Answer 11

TSB > 25 mg/dL

Question 12

What is the definition of extreme neonatal hyperbilirubinemia?

Answer 12

TSB > 30 mg/dL

Question 13

How many days to fetal red blood cells survive compared to adult red blood cells?

Answer 13

Fetal = 85 days

Adult = 120 days

Question 14

What is the typical peak for neonatal TSB?

Answer 14

8-14 mg/dL

Question 15

What enzyme in the liver is responsible for conjugation of bilirubin?

Answer 15

UGT1A1

Question 16

What is the physiologic reason for neonates having increased enterohepatic circulation of bilirubin?

Answer 16

dec. gut bacteria = dec. conversion of conjugated bilirubin to urobilin

inc. deconjugation of bilirubin by intestinal mucosa = inc. enterohepatic circulation

Question 17

What is the physiologic reason for neonates having increased enterohepatic circulation of bilirubin?

Answer 17

dec. gut bacteria = dec. conversion of conjugated bilirubin to urobilin

inc. deconjugation of bilirubin by intestinal mucosa = inc. enterohepatic circulation

Question 18

What is the most common cause of clinically significant unconjugated hyperbilirubinemia?

Answer 18

increased bilirubin production due to hemolytic diseases

Question 19

At what age of life are bilirubin levels typically measured in a newborn?

Answer 19

within 24-48 hours of life

Question 20

What is BIND and what does it stand for?

Answer 20

“Bilirubin-Induced Neurologic Dysfunction”

• unbound bilirubin crosses BBB and binds to brain tissue (basal ganglia and brainstem nuclei)

Question 21

Which two brainstem nuclei are most often involved in bilirubin-induced neurologic dysfunction (BIND)?

Answer 21

Oculomotor and auditory nuclei

Question 22

What is the chronic form of BIND called and what symptoms are characteristically seen with it?

Answer 22

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