When hay fever doesn't quit. Diagnosing seasonal and perennial allergic rhinitis.

Seasonal allergic rhinitis is usually easily diagnosed by the seasonal nature of characteristic symptoms combined with evidence of appropriate specific IgE antibodies. Perennial allergic rhinitis, however, may present a diagnostic challenge. The physician may find IgE antibodies to allergens perennially encountered by the patient and should look for other causes of chronic rhinitis. Examination of nasal secretions can be a diagnostic aid, but measurements of eosinophils and total IgE in serum have limited diagnostic value.