💛 Chapter 15: Jaundice

Nelson's Pediatric Symptom-Based Diagnosis | Unconjugated vs Conjugated · Kernicterus · Biliary Atresia · Crigler-Najjar · Gilbert · Physiologic Jaundice

🔍 Jaundice in Children: Key Concepts

📊 Bilirubin Metabolism
Unconjugated (indirect): lipophilic, not excreted in urine, neurotoxic. Conjugated (direct): water-soluble, excreted in bile/urine. Conjugated hyperbilirubinemia = direct >20% of total or >2 mg/dL.
🔄 Neonatal Unconjugated Hyperbilirubinemia
Physiologic: peaks day 3-5, resolves by 2 weeks. Breastfeeding jaundice (inadequate intake). Breast milk jaundice (late onset, peaks week 2-3). Pathologic: hemolysis (ABO, Rh, G6PD), polycythemia, Crigler-Najjar.
⚠️ Kernicterus (Bilirubin Encephalopathy)
Unconjugated bilirubin crosses blood-brain barrier → basal ganglia, brainstem nuclei. Acute: lethargy, hypotonia, poor feeding, high-pitched cry. Chronic: choreoathetosis, hearing loss, gaze palsy, enamel hypoplasia.
💧 Neonatal Conjugated Hyperbilirubinemia
ALWAYS pathologic. Causes: biliary atresia (urgent Kasai), Alagille syndrome, PFIC, α1-AT deficiency, TPN cholestasis, galactosemia, congenital infections (CMV, toxo).
🧬 Inherited Unconjugated Hyperbilirubinemia
Gilbert syndrome (common, benign, decreased UDPGT activity). Crigler-Najjar type I (no UDPGT activity, severe, kernicterus). Crigler-Najjar type II (partial deficiency, responds to phenobarbital).
🚩 Red Flags in Jaundice
Onset <24h, conjugated hyperbilirubinemia, acholic stools, dark urine, hepatosplenomegaly, poor feeding, lethargy, failure to thrive, family history of liver disease.

💡 Key Takeaway: Conjugated hyperbilirubinemia in a neonate is NEVER physiologic and requires urgent evaluation for biliary atresia. Unconjugated hyperbilirubinemia >20 mg/dL risks kernicterus.

🩺 Clinical Approach to Jaundice: Step-by-Step Algorithm

🔹 Step 1: Conjugated vs unconjugated (fractionated bilirubin)
• Unconjugated: hemolysis (reticulocytosis), Gilbert, Crigler-Najjar, physiologic, breast milk.
• Conjugated (>20% or >2 mg/dL): ALWAYS pathologic. Urgent evaluation.
🔹 Step 2: Neonatal unconjugated – risk of kernicterus
• Phototherapy thresholds based on age, weight, risk factors (hemolysis, prematurity).
• Exchange transfusion if very high levels or signs of acute bilirubin encephalopathy.
🔹 Step 3: Conjugated jaundice in newborn – rule out biliary atresia
• Ultrasound (absent/contracted gallbladder, triangular cord sign).
• Liver biopsy (bile duct proliferation, portal fibrosis).
• Intraoperative cholangiogram (gold standard). Kasai procedure before 60 days.
🔹 Step 4: Older child with conjugated jaundice
• Hepatitis viruses (HAV, HBV, HCV, EBV, CMV), autoimmune hepatitis, Wilson disease, drug-induced, PSC.
🔹 Step 5: Unconjugated jaundice in older child
• Hemolysis (Coombs test, smear, G6PD), Gilbert syndrome (fasting or stress-induced), Crigler-Najjar (persistent severe hyperbilirubinemia).