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Assessing the value of skin prick tests
Clinical Allergy
|March 1, 1980
Summary
Skin reactions of 3 mm or less to common allergens may not indicate a true allergy. Further testing is needed, as these results can be clinically false positives for conditions like milk or egg intolerance.
Area of Science:
- Allergy and Immunology
- Dermatology
- Clinical Diagnostics
Background:
- Skin prick tests are a common diagnostic tool for allergies.
- The interpretation of skin test reaction sizes, particularly 3 mm, can be ambiguous.
- Variability in allergen potency and specificity affects test accuracy.
Purpose of the Study:
- To evaluate the diagnostic significance of different skin test reaction sizes in patients with suspected food intolerance.
- To determine the correlation between skin test results and clinical symptoms or RAST-detectable allergen-specific IgE.
- To assess the prevalence of clinically false positive skin reactions.
Main Methods:
- A study involving 100 allergy clinic patients with reported food intolerance.
- Skin prick testing with various common allergens, including inhalants, milk, egg, and fish.
- Comparison of skin test results with clinical assessment and RAST (Radioallergosorbent Test) for allergen-specific IgE.
Main Results:
- A 3 mm skin reaction to inhalant allergens was often not associated with RAST-detectable IgE.
- 3 mm reactions were significant for milk and egg extracts, correlating with clinical intolerance in many cases.
- Skin reactions of 5 mm or more were more reliable for diagnosing fish allergy, while smaller reactions were unhelpful.
Conclusions:
- Skin test reaction size is critical for accurate allergy diagnosis.
- Reactions smaller than 5 mm, especially to fish, may not be clinically significant.
- A 3 mm reaction requires careful clinical correlation and may indicate false positives for certain allergens.