Assessing the value of skin prick tests.
Skin test materials vary in their potency and specificity. Although 3 mm reactions are often regarded as diagnostic of a type 1 allergy, a study based on 100 allergy clinic patients with food intolerance showed that thirteen out of fifteen patients with a 3 mm reaction to common inhalant allergens had no RAST-detectable allergen-specific IgE. Three millimetre reactions were significant for milk and egg extracts. Food intolerance was clinically demonstrable in six out of seven patients giving a 4 mm skin reaction and in ten out of thirteen with a 3 mm reaction. There was, however, a "clinically false positive" reaction of 3 mm or more in 3.8% of allergy clinic patients for milk and 2.8% for egg. In fifteen out of nineteen patients with a clinical diagnosis of fish allergy, the diagnosis was supported by a skin test reaction of 5 mm or more. However, seven patients with no history of intolerance to fish gave a 4 mm reaction to the same extract. Reactions of less than 5 mm were thus unhelpful clinically.
D000818:Animals; D004531:Eggs / Q000009:adverse effects; D005189:False Positive Reactions; D005399:Fishes; D005512:Food Hypersensitivity / Q000175:diagnosis*; D006801:Humans; D008460:Meat / Q000009:adverse effects; D008892:Milk / Q000009:adverse effects; D009754:Nuts / Q000009:adverse effects; D011852:Radioallergosorbent Test; D012882:Skin Tests