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Asthma

Can Singulair skew serum allergy test results

04/08/2008

Question:

I have intrinsic and extrinsic asthma and have had desensitization for multiple environmental allergies for many years on 2 or 3 times in the past 25 years. My asthma was well controlled until 1 1/2 years ago. When I was sent to a pulmonologist, he ran multiple serum tests (including immunoglobulins and specific allergens like dogs, cats, oaks, grass). I had tested positively to those on the scratch tests, but I was told that now with these serum tests, all were normal. I experience allergy symptoms with exposures to agents. I have been taking Azmacort, Singulair, Spiriva and Prilosec for the past 6 months. Can Singulair or any of these meds produce normal results on serum allergy tests. I think my eosinophylls were also checked and results, normal. Thank you.

Answer:

Singulair should not have an effect on serum allergy tests. When a doctor orders a "blood test" for allergies, most often they are checking a RAST test. This test looks for the protein in your blood (IgE) that joins with an allergen to start an allergic reaction. Treating allergies with immunotherapy or allergy shots can change your IgE, this is one of the goals of treatment.

The question to ask is whether you are still positive by skin tests. Sometime the two (blood and skin tests) don't agree, but not often. If you are not reacting by skin test, then there may be another allergen that is causing your symptoms. Eosinophils should be normal in most people, so this is OK.

I suggest you talk with your doctor about these tests and trying to figure out how to get the right information. This is a case where an allergist may be the best person to help you separate the information and tell you what you are allergic to and what may be leading to some of your symptoms.

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Response by:

David  Hauswirth, MD David Hauswirth, MD
Clinical Assistant Professor
Pulmonary, Allergy, Crtitical Care & Sleep
Pediatrics
College of Medicine
The Ohio State University