Neonatal jaundice from ghai

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Neonatal Jaundice

Note: Ghai's Essential Pediatrics is not available in this library. The following is a comprehensive, standard-curriculum-level coverage drawn from Rosen's Emergency Medicine and The Harriet Lane Handbook (Johns Hopkins), which cover neonatal jaundice in the same depth and framework as Ghai.

Pathophysiology

Bilirubin is formed from the breakdown of heme-containing proteins, primarily hemoglobin. Unconjugated (indirect) bilirubin binds to albumin, is carried to the liver, and is conjugated by UDP-glucuronyl transferase, then excreted into bile.

Three physiologic factors contribute to neonatal jaundice:

Increased bilirubin production (higher RBC mass, shorter RBC lifespan ~70–90 days vs 120 days in adults)
Decreased hepatic clearance and excretion (immature glucuronyl transferase)
Increased enterohepatic resorption (gut flora immature, beta-glucuronidase deconjugates bilirubin back)

Jaundice becomes visible clinically when total bilirubin rises above ~5 mg/dL. Nearly every newborn develops unconjugated bilirubin >1 mg/dL (the adult upper limit) during the first week of life.

Classification

Unconjugated (Indirect) Hyperbilirubinemia

Category	Cause
Benign/physiologic	Physiologic jaundice, breast milk jaundice
Hemolytic	ABO incompatibility, Rh incompatibility, G6PD deficiency, spherocytosis, elliptocytosis, sickle cell, thalassemia, pyruvate kinase deficiency
Birth trauma	Cephalhematoma reabsorption, IVH/ICH
Infectious	TORCHS, UTI, sepsis
Obstructive (enterohepatic)	Meconium ileus, Hirschsprung, pyloric stenosis, duodenal atresia
Metabolic/genetic	Galactosemia, hypothyroidism, Crigler-Najjar syndrome, Gilbert syndrome
Miscellaneous	Dehydration, polycythemia, drugs, hypoalbuminemia, panhypopituitarism

Conjugated (Direct) Hyperbilirubinemia

Always pathologic. Direct bilirubin >2.0 mg/dL and >10% of total serum bilirubin.

Category	Cause
Biliary obstruction	Biliary atresia, choledochal cyst, inspissated bile syndrome, Alagille syndrome
Infectious	CMV, hepatitis B, HSV, rubella, toxoplasmosis, gram-negative sepsis, UTI
Metabolic/genetic	α1-antitrypsin deficiency, galactosemia, tyrosinemia, glycogen storage disease, cystic fibrosis, Dubin-Johnson/Rotor syndrome, Niemann-Pick, Gaucher, Wilson disease
Chromosomal	Trisomy 18, trisomy 21, Turner syndrome
Drugs/toxins	Parenteral nutrition, acetaminophen, erythromycin

Types in Detail

1. Physiologic Jaundice

Occurs in ~50% of normal newborns
Due to immature bilirubin metabolism
Appears after 24 hours of life
TSB peaks at 6–8 mg/dL on days 2–4 in term infants (up to 12 mg/dL in some)
Resolves by 2 weeks in term infants (up to 3 weeks in preterm)
During first 3–4 days: TSB increases to 6.5 ± 2.5 mg/dL; max normal rise rate = 5 mg/dL/24 h or 0.2 mg/dL/h

2. Breast Milk Jaundice

Second most common cause of neonatal jaundice
Pathophysiology uncertain — possibly hormonally mediated or increased enterohepatic resorption
Peaks later (~10–21 days), may persist 3–10 weeks
Mild unconjugated hyperbilirubinemia; infant otherwise well
Treatment: temporary cessation of breastfeeding confirms diagnosis; usually not necessary

3. Pathologic Jaundice — Red Flags

Any jaundice is pathologic if:

Appears within 24 hours of birth
TSB rises >5 mg/dL/24 hr
TSB exceeds exchange transfusion threshold
Persists beyond 3 weeks of age
Associated with direct/conjugated hyperbilirubinemia
Infant appears sick

Risk Factors for Severe Hyperbilirubinemia

Birth weight <2500 g / prematurity
Exclusive breastfeeding
ABO or Rh incompatibility
Cephalhematoma or significant bruising
Predischarge TSB in high-risk zone
G6PD deficiency
Previous sibling requiring phototherapy
Low albumin, sepsis, acidosis
Infant of diabetic mother

Neurotoxicity: BIND and Kernicterus

Unconjugated bilirubin crosses the blood-brain barrier, causing neuronal death. At levels >20–25 mg/dL, risk of bilirubin-induced neurologic dysfunction (BIND) increases.

Acute Bilirubin Encephalopathy (ABE)

Early (potentially reversible):

Somnolence, poor feeding, hypotonia/hypertonia, high-pitched cry

Late (may be irreversible):

Lethargy, hypertonia, retrocollis, opisthotonos, fever, irritability, apnea → seizures → death

Kernicterus

Chronic, irreversible sequelae: cerebral palsy, sensorineural hearing loss, upward gaze palsy, intellectual disability.

Evaluation

Test	Indication
Transcutaneous bilirubinometry	Quick screen in well infants >24h and <7 days old
Total + fractionated serum bilirubin	Confirmation and type (conjugated vs unconjugated)
CBC + peripheral smear	Hemolysis, infection
Direct Coombs test	Isoimmune hemolysis (ABO/Rh)
Blood group (mother + infant)	ABO/Rh incompatibility
Reticulocyte count	Hemolysis
G6PD assay	If risk factors present
Blood glucose, electrolytes, urine reducing substances, ammonia, lactate	Ill-appearing infant (IEM workup)
Urine culture	Conjugated jaundice — exclude UTI
Liver ultrasound	Conjugated jaundice — biliary atresia

Indications for evaluation of a jaundiced infant (Box 166.1):

Jaundice within first 24 hours
Elevated direct bilirubin
Rapidly rising TSB unexplained by history
TSB approaching exchange level or not responding to phototherapy
Jaundice persisting beyond 3 weeks
Sick-appearing infant

Management

General Principle

Goal: prevent BIND and kernicterus. Encourage feeding (including breastfeeding) — stimulates gut motility, reduces enterohepatic recirculation.

Phototherapy

Mechanism: Blue-spectrum light (wavelength ~460 nm) converts unconjugated bilirubin in the skin to water-soluble photoisomers (lumirubin) excreted in bile/urine without conjugation.

Intensive phototherapy should achieve a TSB decline of 1–2 mg/dL within 4–6 hours.

Guidelines for term infants (≥35 weeks) — AAP:

Phototherapy Guidelines — AAP (Rosen's Emergency Medicine)

Guidelines for preterm infants (<35 weeks, Harriet Lane):

Gestational Age	Phototherapy Threshold	Consider Exchange Transfusion
<28 weeks	5–6 mg/dL	11–14 mg/dL
28–29 6/7 weeks	6–8 mg/dL	12–14 mg/dL
30–31 6/7 weeks	8–10 mg/dL	13–16 mg/dL
32–33 6/7 weeks	10–12 mg/dL	15–18 mg/dL

Risk factors that lower threshold: isoimmune hemolytic disease, G6PD deficiency, asphyxia, significant lethargy, temperature instability, sepsis, acidosis, albumin <3.0 g/dL.

Exchange Transfusion (Double-Volume)

Used when phototherapy fails or TSB reaches dangerous levels.

Indications:

TSB continues to rise or remains above exchange threshold despite intensive phototherapy
Signs of acute bilirubin encephalopathy (hypertonia, retrocollis, opisthotonos, fever, high-pitched cry) — immediate exchange transfusion
TSB ≥5 mg/dL above the exchange line

Guidelines for ≥35 weeks gestation:

Exchange Transfusion Guidelines — AAP (Rosen's Emergency Medicine)

Procedure: Double-volume exchange (160–200 mL/kg) removes ~85% of sensitized RBCs and bilirubin-laden blood, replacing it with donor blood.

IVIG (for Isoimmune Hemolytic Disease)

Dose: 0.5–1 g/kg IV over 2 hours
Indicated if TSB is rising despite intensive phototherapy, or TSB is within 2–3 mg/dL of exchange transfusion threshold

Conjugated Hyperbilirubinemia Management

Depends on underlying etiology
Ursodiol for infants on full feeds
Fat-soluble vitamin supplementation (A, D, E, K)
Phototherapy is not contraindicated but risk of "bronze baby" syndrome (transient dark gray-brown discoloration of skin, serum, urine) must be weighed
Biliary atresia: surgical referral (Kasai portoenterostomy) — time-sensitive

Summary Table: Physiologic vs Pathologic Jaundice

Feature	Physiologic	Pathologic
Onset	After 24 hours	Within 24 hours
Peak TSB (term)	≤12 mg/dL	>12 mg/dL
Rise rate	<5 mg/dL/day	>5 mg/dL/day
Duration	<2 weeks (term)	>3 weeks
Bilirubin type	Unconjugated	May be conjugated
General condition	Well infant	May be sick

Sources: Rosen's Emergency Medicine, 9th Ed., Ch. 166; The Harriet Lane Handbook, 23rd Ed., Ch. 18 — Harriet Lane Handbook (Johns Hopkins)

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