IgA

IgA, IgG, or IgM antibody testing.

• To monitor treatment for an insect allergy.
• To measure antibodies that develop in certain infectious diseases, such as aspergillosis, a fungal lung infection, or AIDS.
• To measure the levels of antibodies other than IgE in the blood.
• Rarely used for diagnosis of an allergy.

A sample of blood serum is applied to a plastic disk to which the test antigen or allergen is attached. An enzyme-linked marker is added, which causes a color change if your serum contains antibodies to the antigen tested.

None.

Blood is drawn from your vein and sent to a laboratory for analysis.

Follow procedures for venous blood drawing.

High levels of one type of antibody may prevent low levels of another antibody against the same substance from being detected.

The test demonstrates the amount of IgA, IgG, and IgM antibodies in a milliliter of serum. Interpretation varies with the reason for the test. Since treatment of insect allergies leads to production of IgG, a high level can mean that the treatment is successful. Similarly, since IgG is produced in response to an aspergillosis infection, a high level indicates a recent infection.

• It's relatively inexpensive.
• No radioactive materials are involved.

It does not detect IgE, the antibody most commonly involved in allergic reactions.

• No further testing is necessary, except for monitoring purposes.
• If immunodeficiency is suspected and levels of IgAs are normal, you will be vaccinated and the response to the vaccine will be monitored.