Which lab results suggest Crigler-Najjar syndrome type 2 syndrome?

Updated: May 21, 2019
  • Author: Hisham Nazer, MBBCh, FRCP, DTM&H; Chief Editor: BS Anand, MD  more...
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Crigler-Najjar syndrome type 2 results in lower bilirubin concentrations than does type I, with levels ranging from 7-20 mg/dL. Higher bilirubin levels may be seen if coexisting hemolysis or an intercurrent illness is present.

This disorder may be distinguished definitively from type 1 by chromatographic analysis of pigments excreted in bile. In type 2, bile contains significant amounts of conjugated bilirubin, although the proportion of bilirubin monoglucuronide in bile is increased.

Transferase activity measurements and the response to phenobarbital treatment can also distinguish Crigler-Najjar syndrome type 1 from type 2. Phenobarbital has no effect in type 1 but causes an approximately 25% reduction in plasma bilirubin level in most patients with type 2.

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