Notes · Paediatrics · 6 November 2026

Neonatal jaundice

Definition

• Neonatal jaundice is the clinical manifestation of hyperbilirubinaemia in the first 28 days of life, characterized by yellow discoloration of the skin and sclera due to accumulation of bilirubin, a breakdown product of haemoglobin.
• Bilirubin that is unbound to albumin (free bilirubin) can cross the immature blood‑brain barrier and cause neurotoxicity (kernicterus).

Epidemiology

• Affects > 60 % of term infants and > 80 % of preterm infants within the first week of life.
• Clinically significant hyperbilirubinaemia (requiring phototherapy) occurs in ≈ 10 % of term newborns.
• Higher incidence in Asian, African, and Mediterranean ethnicities due to increased prevalence of haemolytic disorders.

Aetiology (Causes)

• Physiological jaundice – transient rise in bilirubin due to increased red‑cell turnover, immature hepatic conjugation, and reduced enterohepatic circulation.
• Pathological causes – divided into haemolytic and non‑haemolytic categories:
  • Haemolytic: ABO or Rh incompatibility, G6PD deficiency, hereditary spherocytosis, pyruvate kinase deficiency.
  • Non‑haemolytic: Breast‑feeding jaundice (insufficient intake), breast‑milk jaundice (substances in milk inhibiting conjugation), congenital infections (TORCH), metabolic disorders (e.g., hypothyroidism, galactosaemia), liver disease, cephalo‑haematoma, bruising.
• Risk factors – prematurity, low birth weight, exclusive breastfeeding, prolonged labour, birth asphyxia, maternal diabetes, East Asian ethnicity, sibling with severe jaundice, use of certain drugs (e.g., sulfonamides).

Pathophysiology

• Bilirubin is produced from the breakdown of haemoglobin to unconjugated (indirect) bilirubin, which is lipid‑soluble and bound to albumin in plasma.
• The immature neonatal liver has reduced activity of the enzyme uridine diphosphate‑glucuronosyltransferase (UGT1A1), limiting conjugation of bilirubin to water‑soluble direct bilirubin.
• Entero‑hepatic circulation: Unconjugated bilirubin is secreted into bile, re‑absorbed from the intestine, and returned to the liver; newborns have delayed gut motility and high intestinal β‑glucuronidase activity, enhancing re‑absorption.
• When the rate of bilirubin production exceeds hepatic clearance, serum bilirubin rises. If free bilirubin exceeds the binding capacity of albumin, it diffuses into the brain, preferentially depositing in the basal ganglia (kernicterus).

Clinical Features

• Timing:
  • Physiological jaundice appears after 24 h in term infants (usually peaks at 3‑5 days) and after 48 h in preterms.
  • Pathological jaundice often presents < 24 h or rises rapidly (> 0.5 mg/dL per hour).
• Appearance: Yellow discoloration starts on the face and progresses downwards (cephalocaudal spread).
• Severity grading (American Academy of Pediatrics – AAP):
  • Mild: visible on the sclera only.
  • Moderate: visible on the face and chest.
  • Severe: extends to abdomen, thighs, or palms.
• Associated signs: Poor feeding, lethargy, high‑pitched cry, hypotonia, seizures (late sign of neurotoxicity).
• Physical exam: Check for bruising, cephalo‑haematoma, hepatomegaly, splenomegaly, and signs of infection.

Investigations

• Phototherapy threshold (AAP 2022): Use the hour‑specific nomogram; for a term infant (≥ 38 weeks) at 72 h of age, phototherapy is recommended when STB ≥ 15 mg/dL (high‑risk) or ≥ 12 mg/dL (low‑risk).
• Exchange‑transfusion threshold: Typically STB ≥ 20‑25 mg/dL (depending on risk factors) per AAP 2022.

Management

General Principles (Guideline: AAP 2022; NICE 2023)

1. Identify at‑risk infants early – obtain bilirubin level before 24 h if risk factors present.
2. Ensure adequate feeding – 8‑12 mL/kg per feed, ≥ 60 mL/kg/day; promotes stooling and reduces entero‑hepatic recycling.
3. Phototherapy – mainstay for bilirubin > phototherapy threshold.
   • Type: Conventional blue‑light (460‑490 nm) or LED; double‑surface preferred for faster reduction.
   • Intensity: ≥ 30 µW/cm²/nm (irradiance) for effective therapy.
   • Duration: Continue until STB falls below treatment line; monitor every 4‑6 h.
4. Exchange transfusion – indicated when bilirubin exceeds exchange‑transfusion threshold or if there are signs of acute bilirubin encephalopathy.
   • Procedure: Replace infant’s blood with compatible, washed, O‑negative donor blood; volume ≈ 150 mL/kg (≈ 2‑3 total blood volumes).
5. Adjuncts
   • Intravenous immunoglobulin (IVIG) – 1 g/kg single dose for iso‑immune haemolysis when phototherapy is insufficient.
   • Phenobarbital – rarely used; induces UGT1A1, effect seen after 48 h, not first‑line.

Specific Situations

• Breast‑feeding jaundice: Optimize latch, increase feeding frequency; consider supplemental formula if weight loss > 10 % of birth weight.
• Breast‑milk jaundice: Continue breastfeeding; if bilirubin remains > 20 mg/dL after 2 weeks, consider temporary formula supplementation.
• Hemolytic disease: Early phototherapy, IVIG, and possible exchange transfusion; monitor for anemia and treat with packed red cells if needed.

Discharge Criteria

• Stable bilirubin level at least 2 mg/dL below phototherapy line for 12 h.
• Adequate feeding, weight gain, and parental education on follow‑up.

Complications

• Acute bilirubin encephalopathy – neurologic dysfunction (lethargy, hypotonia, high‑pitched cry) due to free bilirubin crossing the blood‑brain barrier.
• Kernicterus – permanent neurologic injury (cerebral palsy, auditory neuropathy, gaze palsy) resulting from chronic exposure to high bilirubin.
• Bronze‑baby syndrome – chronic conjugated hyperbilirubinaemia with copper deposition (rare, seen in cholestasis).
• Phototherapy‑related adverse effects: Dehydration, temperature instability, skin rash, bronze‑skin discoloration, and rare retinal injury (prevent with eye protection).

High‑Yield Exam Points

• Physiological vs. pathological timing – physiological jaundice appears after 24 h in term infants; jaundice < 24 h is pathological until proven otherwise.
• Bilirubin metabolism – unconjugated bilirubin is lipid‑soluble, bound to albumin; conjugated bilirubin is water‑soluble and excreted in bile.
• Key enzyme – UGT1A1 deficiency underlies both physiological immaturity and Crigler‑Najjar syndrome.
• Risk‑based phototherapy thresholds – remember the AAP 2022 nomogram; high‑risk infants (e.g., prematurity, iso‑immune hemolysis) have lower thresholds.
• Kernicterus sites – basal ganglia (globus pallidus), subthalamic nuclei, hippocampus, cerebellar nuclei.
• Management hierarchy – feeding optimisation → phototherapy → IVIG (if immune hemolysis) → exchange transfusion.
• IVIG dose – 1 g/kg single infusion; reduces need for exchange transfusion in iso‑immune hemolysis.
• NICE 2023 recommendation – use transcutaneous bilirubinometry for screening in well‑babies; confirm with serum bilirubin if > 75 th percentile.

Practice questions

1. A 38‑week gestation newborn becomes jaundiced at 18 hours of life with a total serum bilirubin of 13 mg/dL. Which of the following is the most appropriate next step?

• A) Reassure and discharge the baby
• B) Start intensive phototherapy immediately
• C) Obtain a direct Coombs test and repeat bilirubin in 12 hours
• D) Begin exchange transfusion

Answer: C — early onset (< 24 h) suggests pathological jaundice; Coombs test helps identify immune hemolysis and repeat bilirubin guides therapy.

2. According to the AAP 2022 guidelines, a term infant (≥ 38 weeks) at 48 hours of age has a total serum bilirubin of 14 mg/dL and no risk factors. What is the recommended management?

• A) No treatment, observe only
• B) Initiate phototherapy
• C) Perform exchange transfusion
• D) Give oral phenobarbital

Answer: B — bilirubin exceeds the phototherapy threshold for low‑risk term infants at 48 h, so phototherapy is indicated.

3. Which of the following statements about kernicterus is FALSE?

• A) It results from deposition of unconjugated bilirubin in the basal ganglia.
• B) It can be prevented by maintaining serum bilirubin below phototherapy thresholds.
• C) It is reversible once neurological signs appear.
• D) Prematurity increases susceptibility due to a more permeable blood‑brain barrier.

Answer: C — kernicterus causes permanent neurologic damage; it is not reversible after clinical signs develop.

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