eMedicine Specialties > Pediatrics: General Medicine > Allergy & Immunology
Allergic Rhinitis: Differential Diagnoses & Workup
Updated: Jul 13, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
- Multimedia
Differential Diagnoses
| Adenoidal hyperplasia | Nasal Polyps |
| Agammaglobulinemia | Sinusitis |
| Aspergillosis | |
| Cystic Fibrosis | |
| Gastroesophageal Reflux |
Other Problems to Be Considered
Inflammatory causes
Bottle feeding (children >18 mo)
Vasomotor rhinitis
Viral infection
Obstructive causes
Adenoid hyperplasia
Choanal atresia
Foreign body
Deviated septum
Nasal polyps
Neoplasm
Oral allergy syndrome
Oral allergy syndrome (OAS) occurs when the body perceives certain foods, primarily fruits and vegetables, as an allergen and causes a contact dermatitis reaction in the mouth. This is often due to cross-reactivity between pollens and fruit/vegetable allergens. These food allergens are heat labile and easily lose their allergenicity with heating. Thus, patients with this condition report an itchy mouth when eating certain fruits or vegetables in their natural form. For example, eating a whole fresh apple causes a reaction, but eating apple pie or apple sauce or drinking apple juice does not.
The most common pollens associated with OAS include birch and ragweed pollens. Birch tree pollen cross-reacts with apple, pear, peach, celery, and carrots. Ragweed cross-reacts with melon, watermelon, cantaloupe, honeydew, zucchini, and cucumber.
Making the proper diagnosis is important because OAS can be confused with a potentially life-threatening anaphylactic reaction to food allergens. Studies have shown that use of allergen immunotherapy decreases or eliminates this reaction.
Workup
Laboratory Studies
No studies are needed in allergic rhinitis (AR) if the patient has a straightforward history. When the history is confusing, various studies are helpful, including the following:
- Nasal smear: Eosinophils usually indicate allergy. Neutrophils are more indicative of an infectious process, such as sinusitis.
- CBC count with differential: A CBC count may reveal an increased number of eosinophils. An eosinophil count within the reference range does not exclude allergic rhinitis; however, an elevated eosinophil count is suggestive of the diagnosis.
- Immunoglobulin E (IgE): Serum IgE values are not routinely recommended to evaluate atopy. An IgE value within the reference range does not exclude allergic rhinitis; however, an elevated IgE value is suggestive of the diagnosis. Allergen-specific IgE testing, also known as radioallergosorbent test (RAST), can be helpful if a specific allergen is suspected. Screening of a large number of allergens can cause confusion because of the possibility of false positives. This is especially true for IgE food allergy testing.
- Skin prick testing: This test is highly sensitive and specific for aeroallergens.
Imaging Studies
- Imaging studies are not needed unless sinusitis is suspected, in which case, a limited CT scan of the sinuses (without contrast) is indicated.
Other Tests
- RAST for common allergens can be used to identify the patient's triggers. These might include dust mites, cat dander, dog dander, grass pollens, tree pollens, weed pollens, and molds.
- Foods rarely cause allergic rhinitis, and tests for food allergies are not indicated in patients with allergic rhinitis.
- RAST testing for allergens, such as dust mites, cat dander, and dog dander, is almost as sensitive and specific as allergen skin testing.
Procedures
- Skin testing to identify the triggering agent
- Skin testing has high sensitivity and specificity and is the preferred method of quick allergen identification for aeroallergens.
- Skin testing is helpful if the allergens can be eliminated from the patient's environment or if the patient can avoid them.
- Skin testing is extremely helpful when patients are unresponsive to standard therapy or are unwilling to acknowledge the trigger, which is especially true if the family pet is a possible trigger.
- Skin testing is required if the patient is interested in allergen immunotherapy.
- Rhinoscopy: This is helpful in direct examination of the upper airway in identifying whether the etiology of rhinitis is obstructive or infectious and for evaluation of nasal polyposis.
More on Allergic Rhinitis |
| Overview: Allergic Rhinitis |
 Differential Diagnoses & Workup: Allergic Rhinitis |
| Treatment & Medication: Allergic Rhinitis |
| Follow-up: Allergic Rhinitis |
| Multimedia: Allergic Rhinitis |
| References |
| « Previous Page | Next Page » |
References
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Further Reading
Keywords
allergic rhinitis, AR, hay fever, rose fever, spring cold, sneezing, nasal congestion, stuffiness, rhinorrhea, coughing, nasal itch, itchy eyes, scratchy throat, sinus pressure, sinus headache, epistaxis, asthma, sinusitis, atopic dermatitis, otitis media, allergen, allergy, histamine, prostaglandin D2, heparin, platelet-activating factor, cystic fibrosis, dust mites, cat dander, dog dander, indoor molds, cockroaches, tree pollen, grass pollen, weed pollen, allergens, nasal allergies, cigarette smoke, atopic dermatitis, sinusitis, upper respiratory illness, pet allergies, allergic shiners, treatment, diagnosis
