Croup laboratory findings

Laboratory findings may include abnormal white blood cell counts as well as markers for inflammation.

Laboratory tests are rarely useful for diagnosing croup, but the following markers may be present in croup patients.^[1]

• A complete blood count test performed on croup patients may reveal abnormal lymphocyte and other white blood cell counts, lesser or greater than normal.

• Croup patients may display markers for inflammation, determined by the following tests:
  • Erythrocyte sedimentation rate
  • C-reactive protein