allergen skin testing

Indications

• eosinophilic esophagitis
• moderate to severe atopic dermatitis
• assessment of respiratory allergies to pollens & molds
• patients with generalized urticaria, particularly in response to a hymenoptera sting; a large localized reaction does NOT warrant allergen skin testing
• point-of-care beta-lactam allergy skin testing (BLAST)

Adverse effects

• intradermal testing may be associated with potentially life-threatening systemic reactions.

Clinical significance

• positive skin test:
  • identifies allergen-specific IgE
  • does NOT indicate a mucosal immune response to the same antigen under natural conditions
• positive allergen skin testing:
  • 43% of individuals respond positively to at least 1 indoor allergen
  • dust mites 28%
  • cockroach 26%
  • cat 17%

Procedure

• a battery of allergens is applied in a systematic fashion via prick, scratch or intradermal injection usually on the back
• a wheal or a flare indicates an allergic reaction to the injected substance
• reactions are read 15 minutes after injection
• increasing sensitivity is obtained in the order prick < scratch < intradermal injection
• increasing specificity is obtained in the opposite order prick > scratch > intradermal injection

Skin testing should be delayed at least one month after generalized urticaria.

More general terms

• skin testing

More specific terms

• point-of-care beta-lactam allergy skin testing (pocBLAST)
• skin end point titration (Rinkel method)

Additional terms

• radioallergosorbent [RAST] testing