What lab study findings are associated with EGPA (Churg-Strauss syndrome)?

Updated: Dec 02, 2020
  • Author: Spencer T Lowe, MD; Chief Editor: Herbert S Diamond, MD  more...
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In patients with EGPA, the complete blood cell count (CBC) with differential typically demonstrates eosinophilia, usually with at least 10% eosinophils (or 5000-9000 eosinophils/µL), and anemia. The erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) level are usually elevated.

In patients with renal involvement, blood urea nitrogen (BUN) and serum creatinine levels are elevated. Urinalysis demonstrates abnormal urine sediment, proteinuria, microscopic hematuria, and red blood cell casts.

Antineutrophil cytoplasmic antibodies (ANCAs) are present in approximately 40% of patients with EGPA. Most of these patients are perinuclear-ANCA (p-ANCA)–positive (antimyeloperoxidase antibodies). [27]

Other immunologic test results are as follows:

  • Elevated serum IgE levels

  • Hypergammaglobulinemia

  • Positive results for rheumatoid factor at low titer

  • Elevated levels of eosinophil cationic protein (ECP), soluble interleukin-2 receptor (sIL-2R), and soluble thrombomodulin (sTM), which is a marker of endothelial cell damage; elevated ECP and sIL-2R levels indicate an immunoregulatory defect associated with vasculitis and eosinophilia

On bronchoalveolar lavage (BAL), eosinophilia is evident in 33% of cases.

The laboratory tests that might correlate with disease activity include ESR and peripheral blood eosinophilia. In some patients, ANCA titers are related to disease activity.

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