Allergy is the ability of animals and humans to develop altered responses to foreign substances after repeated exposure. It is a hypersensitivity reaction initiated by immunologic mechanisms.
Spectrum of allergen sources
Allergy- Systems Affected
SKIN TEST IS ………
- Confirmatory test
- Low cost
- Highly sensitive
- Factors involved in allergy skin testing
- Quality of allergen extract.
- Diluting fluid.
- False positive reactions.
- Irritating reactions.
- Negative & Positive controls.
Indications of skin prick tests
- To confirm atopy, assisting in the diagnosis of asthma
- Before initiating immunotherapy
- To monitor progress during immunotherapy
- Acute Urticaria & Anaphylaxis
- Occupational Diseases including latex allergy
- Some drug reactions: Penicillin
- Stinging insect anaphylaxis
- Rhinitis vs Sinusitis
SPT is easy to perform and rarely causes generalized reactions. A positive SPT indicates the presence of IgE antibodies against that allergen but does not indicate clinical sensitivity. A correlation between the history and SPT is essential.
The results can be unreliable if the patient takes certain drugs, such as anti-histamines and tricyclic anti-depressants.