To detect antibodies in your blood, blood allergy tests are used to measure these allergen-specific antibodies. Allergy symptoms are caused by these chemicals. The antibody strongly linked to the body’s allergic response is immunoglobulin E or IgE.
Differences between Blood Allergy Tests and Allergy Skin Tests
Even though both blood and skin tests can detect food-specific IgE, their result feedback length is different. For skin tests, the results are immediate, however, a blood test can take a couple of days for the results to arrive. Antihistamines, which are not affected by blood tests, can also be performed on people with rashes, unlike skin tests.
Types of Blood Allergy Tests
A common way to determine the potential of an allergen is through blood testing. Radioallergosorbent testing (RAST) is used to diagnose an allergy, as it looks at the antibodies in your blood to determine the specific allergens causing your allergic reaction. Another test is known as an Enzyme-linked immunosorbent allay (ELISA). This type of test measures the concentration of allergen-specific antibodies in your blood.
Why are Allergy Blood Tests Performed?
There are several reasons why an allergy blood test may be performed, some of which include:
- Certain medicines are known to interfere with test results., like antihistamines, steroids, and certain antidepressants.
- Patients cannot tolerate or are afraid of the many skin pricks used in skin testing.
- An unstable heart condition.
- Uncontrolled asthma.
- Dermatitis, eczema, psoriasis, or other similar severe skin conditions.
- Anaphylaxis, from a history of life-threatening allergic reactions.
When Should I take a Blood Allergy Test?
- If your eyes are red and itchy.
- Persistent coughing, nasal congestion, and sneezing.
- Itchy and/or tingly mouth and throat.
- Vomiting and diarrhea.
As with many other tests, allergy blood tests can have both advantages and disadvantages to them, which can include:
- Regardless of medication, can be done at any time.
- Requires only one needle stick, unlike skin testing.
- Generally more expensive and many health insurers do not cover allergy blood tests, unlike skin tests
- Maybe less sensitive than skin tests