What is the role of eosinophilia testing in the workup of asthma?

Updated: Oct 07, 2019
  • Author: John J Oppenheimer, MD; Chief Editor: Michael A Kaliner, MD  more...
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With the introduction of anti-IL5 agents, measuring an absolute esoniophilc count is useful in helping to phenotype severe asthma and identify potential candidates for targeted therapies. Most institutions do not have the availability of sputum eosinophil measurements.

Decrease in sputum eosinophilia may suggest asthma control or responsiveness to inhaled steroids. However, a study of 50 patients with allergic asthma found no significant correlation between sputum eosinophils measured 7 and 24 hours after bronchoprovocation and early or late bronchoconstrictor responses. [20]

Note that a finding of greater than 1000 eosinophils per microliter of peripheral blood can indicate parasitic infestation, drug allergies, or eosinophilic pulmonary disorders, such as allergic bronchopulmonary aspergillosis or Churg-Strauss syndrome.

Staining nasal secretions with Hansel stain is sometimes used to assess for nasal eosinophilia, but the sensitivity and specificity of this stain are low.

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