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Hyperbilirubinemia. Eric Demers, M.D. 4/17/12. Fetal Development. RBC production begins 2-3 wks (yolk sac). Proceeds to liver (6 wks) and bone marrow (20 wks). Bilirubin present at 14 wks (in amniotic fluid at 12 wks). UVC: bili 1.5 mg/dL @ 20 wks bili 1.8 mg/dL @ term

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Eric Demers, M.D.



Fetal Development

RBC production begins 2-3 wks (yolk sac).

Proceeds to liver (6 wks) and bone marrow (20 wks).

Bilirubin present at 14 wks (in amniotic fluid at 12 wks).

UVC: bili 1.5 mg/dL @ 20 wks

bili 1.8 mg/dL @ term

Fetal RBC lifespan 45-90 days (Premie 35-50 days).

Placenta can remove bilirubin, not biliverdin.



Hyperbilirubinemia occurs in 80% term infants and virtually

all premature infants.

Imbalance between bilirubin production and elimination.

1 g Hemoglobin yields 34 mg bilirubin.

Bilirubin > 25 mg/dL occurs 1 in 750 infants.

Bilirubin > 30 mg/dL occurs in 1-3 per 10,000 infants.


Heme Oxgenase (HO)

HO found in tissue macrophages, GI tract, and reticuloendothelial system.

Rate-limiting step in bilirubin production.

Inhibited by Tin Mesoporphyrin.

Dennery, et. al. J. Perinat. 2001; 21:s17-20.


Bilirubin Transport

Predominantly Albumin: 2 binding sites, 1 high affinity


Ligandin: liver, intracellular transport

P-Glycoprotein (brain) and MRP2: export pump in hepatocytes





Bilirubin Transport:

  • Bilirubin transported in 4 different forms in plasma:
  • Unconjugated bilirubin bound to albumin.
  • Unconjugated bilirubin unbound. (“free”)
  • Conjugated bilirubin.
  • Conjugated bilirubin bound to albumin. (δ-bilirubin)

UDP-Glucuronate β-glucuronosyl Transferase

Bilirubin (insoluble) is glucuronidated in liver twice

Enzyme activity increased with Phenobarbital, Dexamethasone,

Clofibrate, and Thyroid analogs.

Basis for Crigler-Najjar and Gilbert Syndromes.


Defects in UGT:

Bilirubin-UGT1A1 isoform main conjugater.

Located in the Endoplasmic Reticulum of hepatocytes.

Crigler-Najjar type I: complete absence of UGT1A1 activity.

PhototherapyLiver transplantation.

Crigler-Najjar type II: severe but incomplete loss of UGT1A1 activity.

Enzyme inducible with phenobarbital.

Gilbert Syndrome: mildly decreased UGT1A1 activity.

Abnormal promoter. TA(7) Allelle (“Breast Milk Jaundice”)


Enterohepatic Circulation:

Glucuronidated bilirubin is unstable.

Broken down by β-glucuronidase in intestinal mucosal.

(also in breast milk)

In neonates:

1. 10x increased concentration of β-glucuronidase.

2. Alkaline pH of proximal small bowel facilitates

non-enzymatic hydrolysis.

3. Excretion of monoglucuronidated bilirubin (more rapid


Unconjugated bilirubin is readily reabsorbed in intestine.

Accounts for up to 50% hepatic bilirubin load in neonates.

In adults, bilirubin converted by bacteria in intestine to urobilinogen

and stercobilin (both are water-soluble).


Bilirubin Historical perspective:

Neonatal jaundice has been recognized for centuries

First anatomic description of jaundiced brains by Johannes Orth in 1875.

Kernicterus coined in 1904 by Christian Georg Schmorl after

postmortem examination of 120 jaundiced infant’s brains.

1932: Diamond, Blackfan and Baty describe Erythroblastosis


1930-1940: Discovery of Rh antigen.

1940-1950: Use of RBC transfusionsExchange Transfusions (Wallerstein)

1952: Association of serum bilirubin level, Rh disease, and kernicterus established by David Y.Y. Hsia.


Bilirubin Historical Perspective:

1950’s: Kernicterus not restricted to Rh Disease

1950-60’s: Increased understanding of bilirubin metabolism.

1958: Phototherapy for Jaundice. Sister Jean Ward, Dr. Cremer,

and Jerry Lucey (1968).

1964: Rhogam developed (Freda, Gorman, and Pollack).

1970’s: Kernicterus in Premature Infants. (benzyl alcohol)

1980’s: “Disappearance” of Kernicterus.

1990’s: Re-emergence of Kernicterus.


Risk Factors for development of Hyperbilirubinemia:

Dennery, PA, et al. NEJM 2001, 344(8):581-90.


The Bilirubin Set-up:

  • Neonates have:
  • Shortened RBC survival. (approx. 70 days)
  • Increased RBC mass.
  • Immaturity of hepatic glucuronidation.
  • Enhanced enterohepatic circulation.
  • Feeding issues: Breast feeding, dehydration, etc.

“Bilirubin 20 mg/dL = Vigintiphobia”

Jon F. Watchko and Frank A. Oski

Pediatrics 1983, 71(4): 660-3

Challenged premise that bilirubin > 20 mg/dL requires exchange

transfusion. (Data extrapolated from Rh Disease.)

Hsia et al. 1952: Rh disease, 18% infants with bilirubin 16-30 mg/dL

and 50% infants with bilirubin > 30 mg/dL developed kernicterus.


Evaluation of Jaundiced Newborn:

Bilirubin level: plasma

Mother-Baby studies: Mom and infant’s blood type and direct Coombs.

CBC with smear.

Reticulocyte count.


Hour-Specific Bilirubin:

Healthy, dCoombs neg.

N = 2840 (13,003)

High Risk: (> 95%)

TSB > 8 mg/dL @ 24 hrs.

TSB > 14 mg/dL @ 48 hrs.

TSB > 17 mg/dL @ 84 hrs.

Bhutani, et al. Pediatrics 1999; 103(1): 6-14.



  • Nutrition: Breast vs. Bottle feeding vs. IV fluids.
  • Phototherapy
  • Inhibitors of hemoglobin degradation (Tin Mesoporphyrin).
  • Stimulators of hepatic UDPG enzyme (Phenobarbital).
  • Exchange Transfusion.
  • IVIG: Rh disease or ABO hemolytic disease.

Breast Feeding:

Breast Feeding Jaundice: first 5 days of life.

Breast Milk Jaundice: 4-7 days of life. (can persist for weeks)

Likely Gilbert + G6PD deficiency

Average weight loss: 6.1% ± 2.5%. 5-10% BF infants lose > 10%

Breast fed infants are 3x more likely to develop TSB > 12 mg/dL,

6x more likely to develop level > 15 mg/dL versus formula fed.

Increasing the frequency of BF during first several days of life

decreases TSB levels.( at least 8 times/24 hr period)

Supplemental feedings of water or dextrose-water increase TSB.

Interrupt nursing?...Probably not unless TSB > 25 mg/dL.



Cremer study 1958. Not used in US until Lucey’s study 1968.

Factors: (from Maisels)

Light source (Spectrum): 480-500 nm best (blue-green)

Blue fluorescent tubes (special): as close as 10 cm

from baby

Halogen: risk of burns

Fiberoptic: Wallby™ and BiliBlanket™

Light-emitting diodes

Dose (Irradiance)

Design of Phototherapy

Exposed surface area in infant

Distance of light source from infant



How does it work: bilirubin Z,Z

Photodegradation: Z-Lumirubin (2-6%), more rapid clearance.

Photooxidation (to biliverdin and others): slow process

Photoisomerization: Increased polarity (solubility), does not

require liver conjugation. (20%). Bilirubin Z,E.

Reversible process.

How effective: Very. Lowers bilirubin by up to 50% first 24 hrs.

Side Effects:

Cell/DNA damage


Bronze Baby Syndrome

Eye Damage: Retina


Insensible water loss/thermoregulation

Blunts postprandial increase in SMA blood flow



Competitive inhibitor of HO. Allows heme to be eliminated directly.

One dose effective at preventing extreme hyperbilirubinemia.

preventive dose: 1-6 µmol/kg

treatment dose: 6 µmol/kg

Rapidly cleared from plasma but prolonged half-life. (photosensitivity)

Concerns about heme homeostatic disruption.

Currently not FDA approved


Exchange Transfusion:

Goals:(Watchko in Neonatal Jaundice, 2000.)

1. Removal of antibody-coated RBCs.

2. Correction of anemia.

3. Removal of maternal antibody.

4. Removal of other toxic byproducts of hemolytic process.

~85% infant’s RBCs removed by double-volume exchange. (DVE)

Majority of bilirubin is extravascular

DVE removes 110% circulating bilirubin (25% total body)

Post-exchange bilirubin levels ~60% pre-exchange.

30 min post-exchange, serum bili 70-80% pre-exchange.

Perform through UVC. Duration: 1.5 +/- 0.5 hrs.


Exchange Transfusion:

Many complications:

Hypocalcemia: 5%





Catheter-related complications



Altered blood flow


Death: 0.3-0.95 per 100 procedures

Significant Morbidity: 6.7%


ABO Incompatibility:

Mom O and Baby A or B represents ABO incompatibility.

A>B for antigenicity.

Neonates have fewer A, B antigens compared to adult RBCs.

15% pregnancies at risk.

1/3 A or B infants born to O mothers have positive Direct Coombs.

1/5 with positive Coombs develop modest to significant degree of hyperbilirubinemia. (TSB > 12.8 mg/dL)


Coombs Testing:

Direct Coombs: Recognizes antibodies on fetal RBC’s. Steps 2,3

Indirect Coombs: Recognizes antibodies in maternal serum. Steps 1-3

Blue: Maternal Antibodies

RBC: Neonate’s RBCs

Green: Coombs Reagent


Rh Disease:

  • Risk if mom is Rh neg. and baby is Rh positive. (15% Caucasians are.)
  • Major antigen is D. (but other antigens exist)
  • Prevent with Rhogam.(10 µg/ml fetal blood or standard dose is 300 µg)
  • To develop Rh Disease, need: (From Gabbe, 2002)
  • The fetus must have Rh-positive erythrocytes, and the mother must have
  • Rh-negative erythrocytes.
  • 2. A sufficient number of fetal erythrocytes must gain access to the maternal
    • circulation. (as little as 0.1 ml fetal blood)
  • The mother must have the immunogenic capacity to produce antibody
  • directed against the D antigen.

Glucose-6 Phosphate Dehydrogenase Deficiency (G6PD):

X-linked recessive. Most common enzyme defect.

3.4% incidence (up to 20% with specific populations)

Mediterranean, Africa, SE Asia, Arab.

Class 1: severe deficiency, lifelong hemolysis/anemia

Class 2: severe deficiency, 1-10% enzyme activity

Class 3: moderate deficiency, 10-60% enzyme activity

Class 4: Normal, 60-150% enzyme activity

Class 5: Increased, >150% enzyme activity

Activity of enzyme declines with increasing age of RBC.

Hemolysis triggered by oxidative exposure.

Increased risk of sepsis (unknown mechanism)

Bhutani, V. Neoreviews 2012, 13(3):e166-77.

g6pd continued
G6PD continued

Bhutani, V. Neoreviews 2012, 13(3):e166-77.

g6pd cont
G6PD cont



Fluorescent Intensity (FST) of NADPH-not useful

with partial enzyme activity, semi-quantitative

Quantitative: Several methods, preferred

*Specrophotometric assay for NADPH formation*

PCR: too many mutations (~ 127 identified to date) but useful confirmation and in females


Kernicterus: “Jaundice of the Nuclei”

Bilirubin highly toxic to neurons, particularly in certain regions of

the brain.

Toxicity enhanced by acidosis, infection, respiratory compromise,

dehydration and hyperosmolarity.

Regions affected include: hippocampus, thalamus, striatum, auditory and oculomotor nuclei.

Kernicterus has both acute and chronic components.


Bilirubin Neurologic Toxicitiy:

Acute Phase: (“Acute Bilirubin Encephalopathy”)

Early: Lethargy, hypotonia, poor suck

Intermediate: Moderate stupor, irritability, hypertonia. May have

fever, high-pitched cry, altered MS

Advanced: Retrocollis-Opisthotonos, shrill cry, no feeding,

apnea, fever, deep stupor/coma, seizures, death

Chronic Phase: (“Kernicterus”)

a. Deafness/auditory system dysfunction (high frequency,

sensorineural hearing impairments.)

b. Movement disorders: Athetosis, dystonia, hypotonia

c. Oculomoter disturbances: particulary upward gaze paresis

d. Dental enamel hypoplasia of deciduous teeth




Striatum, Hippocampus


MRI and Kernicterus:

Axial T2-weighted image

Axial T1-weighted image

Shah, Z et al. Australian Radiology 2003; 47(1):55-7.


Kernicterus Registry

Created in 1992 by Dr. Audrey.K. Brown and colleagues.

Analyzed through January 1, 2001.

Only 1/61 initial patients delivered by C/S.

59/61 initial patients were breast fed.

Pre-discharge bilirubin level in 26% (16/61).

10/16 level was > 95% on Hour-Specific Bilirubin Nomogram.

44/61 (72%) did not have follow-up appointment within 2-3 days.

20.8% subsequently found to have G6PD

Johnson, LH et al. J. Pediatr. 2002; 140(4):396-403.


“It’s natural for babies to be sleepy”

“Most babies are jaundiced”

“Jaundice gets worse before it gets better.”

“Don’t worry as long as the baby is feeding, wetting diapers,

and stooling.”

“No need to bring the baby in to see the doctor”

“Try not to be an overanxious mother”

Johnson, LH et al. J. Pediatr. 2002; 140(4):396-403.


Root Causes in Reappearance of Kernicterus:

JCAHO Sentinel Event Alert, April 2001, issue 18

  • Patient Assessment:
  • a. Unreliability of visual assessment of jaundice in newborns
  • with dark skin.
  • b. Failure to recognize jaundice or severity based on visual
  • assessment and measure bilirubin level before d/c or at f/u.
  • c. Failure to measure bilirubin level in infant who is jaundiced
  • in first 24 hrs. of life.

Root Causes in Reappearance of Kernicterus:

JCAHO Sentinel Event Alert, April 2001, issue 18

2. Continuum of Care:

a. Early hospital d/c (<48 hrs.) without appropriate

f/u (1-2 days after d/c). Particularly in infants

< 38 wks.

b. Failure to provide early f/u with physical assessment for infants who are jaundiced before d/c.

c. Failure to provide ongoing lactation support.


Root Causes in Reappearance of Kernicterus:

JCAHO Sentinel Event Alert, April 2001, issue 18

3. Patient and Family Education:

a. Failure to educate parents about jaundice

b. Failure to respond appropriately to parental concerns

about jaundiced newborn, poor feeding, lactation difficulities or changes in newborn behavior and activity.


Root Causes in Reappearance of Kernicterus:

JCAHO Sentinel Event Alert, April 2001, issue 18

4. Treatment:

a. Failure to recognize, address or treat rapidly rising bilirubin.

b. Failure to aggressively treat severe hyperbilirubinemia in a timely fashion with intensive phototherapy or exchange transfusion.


PICK: Parents of Infants and Children with Kernicterus

Founded in 2000 by seven mothers.

Organized workshop on Hyperbilirubinemia/Kernicterus in 2001

attended by CDC, JCAHO, NIH, AAP, researchers, etc.

Worked with JCAHO to issue Sentinel Event Alert May 2001.

Advocated for classification of kernicterus as “Never Event” by

National Quality Forum (NQF).

Worked with CDC to issue MMWR on kernicterus on June 2001.

Worked to educate multiple organizations about hyperbilirubinemia

and kernicterus.

Initiated research on kernicterus.


Major Risk Factors for Hyperbilirubinemia in Full-Term Newborns

Jaundice within first 24 hours after birth.

Asibling who was jaundiced as a neonate.

Unrecognized hemolysis such as ABO blood type incompatibility or

Rh incompatibility.

Nonoptimal sucking/nursing.

Deficiency in glucose-6-phosphate dehydrogenase, a genetic disorder.

I nfection.


East Asian or Mediterranean descent.

MMWR 2001, 50(23): 491-4.


July 2004 AAP Guidelines

“Management of Hyperbilirubinemia in the Newborn

Infant 35 or More Weeks of Gestation”

Pediatrics, 2004; 114(1): 297-316.