Allergy testing Service
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At Slough pharmacy we more often than not use the Skin Prick Testing (SPT) method of allergy testing to diagnose common food, inhalant and environmental allergies.
The usual test site for allergy testing using the SPT method is the skin of the inner forearm. Allergy testing is possible using blood sample to measure Total Immunoglobulin E (IgE) which is the marker antibody for allergy sensitisation. Food Allergy screens, Phadiatop inhalant screen and over 450 individual RAST or ImmunoCAP tests are there too.
Allergy severity can be quantified using another cellular marker, the Eosinophil cell in the blood stream. Eosinophils are also present in the allergy sufferer’s phlegm, nasal mucous and gullet secretions. Lung function tests are vital in asthma diagnosis, and tests include Forced Vital Capacity (FVC), Peak Flow (PF) and Forced Expiratory Volume in 1 second (FEV1). Measurement of NO (Nitric Oxide) in exhaled air is another measure of allergic inflammation and points to poor control or futile treatment.
Another way of determining if somebody is allergic to a substance is to directly challenge him or her with that very substance. This is called Provocation or Challenge allergy testing and is regarded as the Gold Standard in allergy diagnosis. But this is only recommended in a controlled hospital environment as it can be unsafe and trigger a severe allergic reaction. Challenge tests include lung, nasal and conjunctiva challenges with the suspected allergen (for instance pollen and mould spores) and DBPCFC (Double Blind Placebo Controlled Food Challenge) tests for suspected food allergy.
A positive allergy test points to sensitisation to an allergen but does not essentially predict that a clinically relevant allergic reaction will befall. That is the reason why general allergy testing in otherwise healthy individuals is thoroughly discouraged, as the results might be deceptive. One should never shy away from questioning whether specific allergy symptoms can be associated to a particular allergy test result, and there can be absolutely no substitute for an expert allergist with some years of experience in allergy testing, diagnosis and treatment. Slough pharmacy has some very experienced allergists.
Skin Prick or Scratch Allergy Testing
Skin Prick Testing (SPT) is regarded as the most highly sensitive allergy test available despite being one of the oldest allergy tests available and quite naturally is the cornerstone of primary care allergy diagnosis.
Atopy Patch Tests
Atopy Patch Tests (APT) on the skin is capable of detecting delayed hypersensitivity reactions to foods but are usually used to detect trigger contact allergens such as rubber, nickel, dyes and cosmetics. However a newer application of this patch test is to test for food allergens particularly where a delayed (non-IgE) hypersensitivity reaction is suspected in children.
Blood Testing for Allergy
The original Total serum IgE blood test has been rendered archaic by the newer multi-allergen screening tests. The inhalant allergy screen is termed ImmunoCAP Phadiatop and there are many ImmunoCAP food allergy screening panels.
Allergy testing for childhood Food Allergy
Most common Paediatric Food Allergy screening test fx5 includes the commonest 6 implicated allergy-provoking foods (Cow’s Milk protein, Wheat, Codfish, Hens Egg white, Peanut and Soya bean). These foods account for about 90% of IgE mediated food allergy in young children.
