Thank you for your inquiry.
Repeat allergy testing, either by in vivo or in vitro techniques, is not routinely performed in patients who have been tested once and placed on allergen immunotherapy based on these tests. That is, repeat testing is not routinely recommended to assess the progress or efficacy of allergen immunotherapy. There are possible exceptions to this rule which could include, but possibly be not limited to:
1. A child who is tested at an early age and shows only positive testing to indoor allergens, but who later develops symptoms consistent with exposure to outdoor aeroallergens.
2. A child or an adult who moves to a geographical area containing allergens to which they have not previously been exposed but to which they demonstrate symptoms upon exposure.
3. The development and availability of a superior, purified, or better standardized allergen for testing in a patient who has clinical symptoms upon exposure to this allergen, but a previously negative skin test when tested to the older, less standardized or purified extract.
4. A patient on allergen immunotherapy who, after initiation of immunotherapy, obtains an indoor pet, the exposure to which induces symptoms, and who had a previously negative skin test to the pet, and therefore whose vaccine does not contain the pet allergen.
But, as noted, there is no indication for routine retesting of patients who have been on allergen immunotherapy based on previous results of testing.
Thank you again for your inquiry and we hope this response is helpful to you.
Phil Lieberman, M.D.