Interpreting conjugated bilirubin levels in newborns

J Pediatr. 2011 Apr;158(4):562-565.e1. doi: 10.1016/j.jpeds.2010.09.061. Epub 2010 Nov 12.


Objective: To examine the clinical significance of elevated conjugated bilirubin (CB) levels in newborns.

Study design: This retrospective study evaluated a birth cohort of 271 186 full-term newborns born within a Northern California hospital network from 1995 to 2004. All CB and direct bilirubin (DB) levels were available in a database and were correlated with the patients' inpatient and outpatient International Classification of Diseases, 9th Revision diagnoses.

Results: The 99th percentile for CB is 0.5 mg/dL, and the 99th percentile for DB is 2.1 mg/dL. CB levels between 0.5 and 1.9 mg/dL can be associated with infection, but most often remain unexplained. Liver and biliary disease become increasingly likely as CB levels increase; for CB ≥5 mg/dL, 47% of newborns have biliary disease and 43% have liver disease.

Conclusions: CB and DB levels are not interchangeable. In newborns with CB levels ≥0.5 mg/dL and <2 mg/dL, infection must be ruled out, and the newborn should be observed. In newborns with levels ≥2 mg/dL, a more in-depth assessment of the hepatobiliary system is indicated.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Bilirubin / blood*
  • Cholestasis / diagnosis
  • Female
  • Humans
  • Infant, Newborn
  • Jaundice, Neonatal / diagnosis
  • Male
  • Reference Values
  • Retrospective Studies


  • Bilirubin