From the Guidelines
To diagnose allergic rhinitis and treat symptoms that do not respond to medical and environmental control treatments, the family nurse practitioner should refer the patient for skin testing. This recommendation is based on the clinical practice guideline for allergic rhinitis, which suggests that specific IgE (skin or blood) allergy testing should be performed for patients who do not respond to empiric treatment, or when the diagnosis is uncertain, or when knowledge of the specific causative allergen is needed to target therapy 1. Skin testing is considered the gold standard for identifying specific allergens causing allergic rhinitis when standard treatments have failed. The benefits of skin testing include:
- Direct observation of the body's allergic response to various allergens
- Comprehensive and immediate results for identifying specific allergen sensitivities
- Ability to implement targeted interventions such as allergen avoidance strategies or immunotherapy (allergy shots) to address symptoms that haven't responded to conventional treatments. While other diagnostic options like nasal smears for eosinophils, serum IgE levels, or RAST testing can provide useful information, skin testing offers the most effective approach for personalized management of persistent allergic rhinitis symptoms, as supported by randomized controlled trials and systematic reviews 1.
From the FDA Drug Label
Clemastine Fumarate Syrup is indicated for the relief of symptoms associated with allergic rhinitis such as sneezing, rhinorrhea, pruritus and lacrimation. The family nurse practitioner would consider referring for skin testing to diagnose allergic rhinitis and treat symptoms that do not respond to medical and environmental control treatments.
- This is because the provided drug label does not directly address diagnostic methods, but skin testing is a common method for diagnosing allergies. 2
From the Research
Diagnostic Approaches for Allergic Rhinitis
To diagnose allergic rhinitis and treat symptoms that do not respond to medical and environmental control treatments, the family nurse practitioner may consider the following options:
- Obtain a nasal smear for eosinophils
- Order serum immunoglobulin E (IgE) level to environmentals
- Refer for skin testing
- Order a serum radioallergosorbent testing (RAST)
Skin Testing vs. Serum-Specific IgE Testing
Studies have compared the effectiveness of skin testing and serum-specific IgE testing in diagnosing aeroallergen sensitization and predicting clinical allergy. According to 3, skin testing was more sensitive than RAST for all four indoor allergens tested. Similarly, 4 states that skin tests are used to exclude or confirm immunoglobulin E (IgE) mediated diseases, such as allergic rhinitis.
RAST and Its Significance
The Radio Allergo Sorbent Test (RAST) is a radioimmunological in-vitro test for determining IgE specific serum antibodies in reaginic allergy 5. The overall correspondence between RAST and skin tests was 70.2%, with the agreement between positive RAST and skin tests being 22.1%.
Current Recommendations
Currently, testing for immunoglobulin E (IgE) sensitization is the cornerstone of diagnostic evaluation in suspected allergic conditions 6. Skin prick testing remains the first line approach in most instances. The added value of serum specific IgE to whole allergen extracts or components is also evaluated.
Comparison of Diagnostic Tests
A review article provides a detailed summary of recent studies addressing the question of which testing method, skin or serum testing, is superior in diagnosing allergic sensitization 7. The studies show substantial discordance between serum-specific IgE and skin testing results, suggesting that the two testing methods complement each other and cannot be used interchangeably.