Seeking allergy when it hides: which are the best fitting tests?

Area of Science:

• Immunology
• Allergology
• Otorhinolaryngology

Background:

• Standard allergy diagnosis relies on IgE tests, but some patients with symptoms and suggestive histories test negative.
• This often leads to misdiagnosis as nonallergic rhinitis or asthma, potentially delaying appropriate allergic management.
• Local allergic rhinitis and T cell-mediated hypersensitivity are underdiagnosed mechanisms in respiratory allergies.

Purpose of the Study:

• To highlight the limitations of conventional IgE testing in diagnosing respiratory allergies.
• To emphasize the importance of additional diagnostic methods for patients with negative IgE results.
• To discuss the role of local allergic rhinitis and delayed hypersensitivity in misdiagnosed cases.

Main Methods:

• Review of diagnostic approaches for respiratory allergies, focusing on IgE testing limitations.
• Discussion of alternative diagnostic tools: nasal IgE measurement, nasal provocation tests, and atopy patch tests (APT).
• Analysis of clinical scenarios where IgE-negative patients may have underlying allergic mechanisms.

Main Results:

• Local allergic rhinitis, characterized by IgE production in the nasal mucosa, requires specific nasal testing for diagnosis.
• T cell-mediated delayed hypersensitivity, often linked to atopic dermatitis history, can be identified via APT.
• House dust mites are a common allergen in APT-positive patients, but other allergens can also be involved.

Conclusions:

• Patients with suggestive allergy symptoms but negative IgE tests may still have allergies.
• Nasal IgE measurements, nasal provocation tests, and APT are crucial for accurate diagnosis in such cases.
• Accurate diagnosis is vital to prevent adverse outcomes related to allergen avoidance, education, and immunotherapy.