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Principal differential characteristics of inherited unconjugated hyperbilirubinemia

Principal differential characteristics of inherited unconjugated hyperbilirubinemia
  Crigler-Najjar syndrome type I Crigler-Najjar syndrome type II Gilbert syndrome
Epidemiology and natural history
Mode of inheritance Autosomal recessive Autosomal recessive Autosomal recessive
Prevalence Rare Rare Common (approximately 9% of White people are homozygous for a variant TATAA box; 4 to 5% have hyperbilirubinemia)
Prognosis Kernicterus, unless vigorously treated Usually benign, kernicterus occurs rarely Benign
Routine clinical evaluation
Serum bilirubin concentration* 20 to 50 mg/dL
(340 to 850 micromol/L)
Usually 8 to 20 mg/dL
(136 to 340 micromol/L)
Usually <3 mg/dL
(<51 micromol/L)
Routine liver function tests Normal Normal Normal
Effect of phenobarbital on serum bilirubin None Reduction Reduction
Tests not routinely performed
Bilirubin glucuronides Usually pale; contains small amounts of unconjugated bilirubin Bilirubin glucuronides present: Increased proportion of bilirubin monoglucuronide Bilirubin glucuronides present: Increased proportion of bilirubin monoglucuronide
Liver histology Normal, but fibrosis is present in approximately 40% of cases[1] Normal Normal
Hepatic bilirubin UGT activity Absent Markedly reduced (10% of normal) Reduced (30% of normal)
45-min plasma BSP retentionΔ Normal Normal Usually normal; may be prolonged
UGT: uridine diphosphate glucuronosyltransferase; BSP: bromosulfophthalein.
* Serum bilirubin concentrations depend on age and optimal medical management. In each of these disorders, further acute elevations may occur, triggered by fasting or intercurrent illnesses. The risk of severe acute exacerbations (eg, bilirubin >20 mg/dL) and resulting kernicterus is high for Crigler-Najjar syndrome type I, low for Crigler-Najjar syndrome type II, and absent for Gilbert syndrome.
¶ Bilirubin glucuronides are measured by high-pressure liquid chromatography (HPLC) of bile collected from the duodenum.
Δ Plasma BSP retention is prolonged in Dubin-Johnson and Rotor syndromes, and in hepatobiliary cholestatic disorders.
Reference:
  1. Mitchell E, Ranganathan S, McKiernan P, et al. Hepatic Parenchymal Injury in Crigler-Najjar Type I. J Pediatr Gastroenterol Nutr 2018; 66:588.
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