Prolonged neonatal jaundice

Visible icterus in a newborn that persists beyond 2 weeks in a formula-fed infant, or beyond 3 weeks in a breastfeeding infant. Physiologic and breast-milk jaundice are common and benign; the work is to find the small subset whose persistent jaundice is the visible sign of a treatable or time-sensitive disorder. The single most important first step is fractionating the bilirubin into unconjugated and conjugated (direct). A conjugated (direct) hyperbilirubinemia of any degree (direct > 1 mg/dL if total < 5, or direct > 20% of total) in a neonate is pathological and is biliary atresia until proven otherwise, because the Kasai portoenterostomy outcome plummets after about 60 days of life.

The mechanistic split is simple and load-bearing:

1. Unconjugated (indirect) hyperbilirubinemia: uptake, conjugation, or hemolysis problem. Usually benign in the neonate, occasionally serious (Crigler-Najjar, hemolysis, hypothyroidism).
2. Conjugated (direct) hyperbilirubinemia: structural biliary disease, hepatocellular disease, or storage disorder. Always pathological. Time-sensitive.

If the bilirubin is conjugated, the next questions are: are stools acholic (biliary obstruction signal)? Are there dysmorphic features? Is there failure to thrive, bleeding (vitamin K deficiency from cholestasis), hypoglycemia, cataracts, sepsis?

Unconjugated hyperbilirubinemia

• Breast milk jaundice: the most common cause of prolonged unconjugated jaundice. Healthy thriving infant, otherwise well; resolves over weeks.
• Crigler-Najjar syndrome (UGT1A1, AR): severe deficiency of UDP-glucuronosyltransferase.
  • Type I: near-complete enzyme absence; severe unconjugated hyperbilirubinemia, kernicterus risk, requires phototherapy or transplant.
  • Type II (Arias): partial deficiency; responds to phenobarbital (induces residual enzyme).
• Gilbert syndrome (UGT1A1 promoter polymorphism, AR): mild intermittent unconjugated hyperbilirubinemia, common, benign.
• Hemolytic disorders: ABO/Rh incompatibility; G6PD deficiency; hereditary spherocytosis; pyruvate kinase deficiency. Reticulocytosis and abnormal smear are the screen.
• Congenital hypothyroidism: prolonged jaundice, hypotonia, large fontanelles, umbilical hernia, coarse cry. Newborn screen catches most.

Conjugated (direct) hyperbilirubinemia

• Biliary atresia: the time-sensitive must-not-miss. Idiopathic progressive obliteration of extrahepatic bile ducts. Acholic stools, hepatomegaly, conjugated jaundice. Kasai portoenterostomy works best before 60 days of life; after 90 days, transplant outcomes dominate. The single highest-yield bedside clue is acholic (pale, putty-colored) stool.
• Alagille syndrome (JAG1, AD; rarely NOTCH2): paucity of intrahepatic bile ducts + butterfly vertebrae + posterior embryotoxon + peripheral pulmonic stenosis + characteristic triangular facies. Conjugated jaundice in the first months.
• Progressive familial intrahepatic cholestasis (PFIC):
  • PFIC1 (ATP8B1): low GGT cholestasis.
  • PFIC2 (ABCB11, BSEP): low GGT, severe early cholestasis, HCC risk.
  • PFIC3 (ABCB4, MDR3): high GGT cholestasis.
  • PFIC4-6 (TJP2, NR1H4, MYO5B): rarer.
• Alpha-1-antitrypsin deficiency (SERPINA1, PiZZ homozygote): neonatal cholestasis in ~10% of PiZZ neonates, then progresses to childhood / adult liver disease + emphysema later.
• Cystic fibrosis (CFTR): meconium ileus and prolonged cholestasis; newborn screen and immunoreactive trypsinogen catch most.
• Classic galactosemia (GALT, AR): jaundice + E. coli sepsis + cataracts + hepatomegaly after milk feeds begin. Medical emergency: switch to soy formula at suspicion, do not wait for the confirmation.
• Tyrosinemia type 1 (FAH, AR): acute liver failure picture with conjugated jaundice; succinylacetone in urine is diagnostic; treatable with nitisinone.
• Citrin deficiency (SLC25A13, AR): neonatal intrahepatic cholestasis (NICCD); resolves in many but recurs as adult-onset citrullinemia type II.
• Mitochondrial DNA depletion syndromes: POLG, MPV17, DGUOK (Alpers-like / hepatocerebral phenotypes); cholestasis + lactic acidosis + neurologic features.
• Niemann-Pick disease type C (NPC1, NPC2): neonatal cholestasis (sometimes severe) + hepatosplenomegaly + later neurodegeneration with vertical supranuclear gaze palsy.
• Panhypopituitarism / septo-optic dysplasia: prolonged cholestasis + hypoglycemia + midline defects + nystagmus / wandering eyes; cortisol and TSH/T4 deficient.
• Sepsis, UTI, TORCH infections (CMV, toxoplasma, syphilis, HSV): acquired causes; never miss because each has specific treatment.

1. Fractionated bilirubin (total and direct/conjugated) is the first test. Repeat if equivocal.
2. Stool color assessment (parents' descriptions are unreliable; show them a color card or photograph).
3. Liver enzymes (ALT, AST), GGT, alkaline phosphatase, albumin, INR, glucose: high GGT cholestasis (biliary atresia, Alagille, PFIC3) vs low GGT cholestasis (PFIC1, PFIC2, bile acid synthesis defects).
4. CBC, reticulocyte count, blood smear, Coombs: hemolysis screen.
5. TSH, free T4 (congenital hypothyroidism).
6. Newborn screen review (galactosemia, CF, tyrosinemia, hypothyroidism, hemoglobinopathy).
7. Urine reducing substances + urine succinylacetone (galactosemia, tyrosinemia).
8. Abdominal ultrasound (after 4-hour fast): biliary anatomy, presence of gallbladder (absent or small in biliary atresia), triangular cord sign, choledochal cyst.
9. Hepatobiliary scintigraphy (HIDA scan) after phenobarbital priming if biliary atresia suspected.
10. Alpha-1-antitrypsin level and PI typing, sweat chloride (CF), plasma amino acids, acylcarnitine profile, cortisol, TORCH titers, urine CMV PCR.
11. Liver biopsy if non-invasive work-up is inconclusive (paucity of bile ducts in Alagille; ductular reaction and bile plugs in biliary atresia).
12. Targeted cholestasis gene panel or trio exome if no diagnosis at 4-6 weeks.