An IgA test measures the blood level of immunoglobulin A, one of the most common antibodies in the body. Antibodies are proteins made by the immune system to fight bacteria, viruses, and toxins.
IgA is found in high concentrations in the body's mucous membranes, particularly the respiratory passages and gastrointestinal tract, as well as in saliva and tears.
IgA also plays a role in allergic reactions. Its levels rise in response to the presence of allergens, such as pet dander, in sensitive people. IgA levels also may be high in autoimmune conditions, disorders in which the body mistakenly makes antibodies against healthy tissues.
An IgA test can help doctors diagnose problems with the immune system, intestines, and kidneys. It's also used to evaluate autoimmune conditions, such as rheumatoid arthritis, lupus, and celiac disease. Kids born with low levels of IgA — or none at all — are at increased risk of developing an autoimmune condition.
Your doctor will tell you if any special preparations are required before this test. On the day of the test, it may help to have your child wear a short-sleeve shirt to allow easier access for the technician who will be drawing the blood.
A health professional will usually draw the blood from a vein. For an infant, the blood may be obtained by puncturing the heel with a small needle (lancet). If the blood is being drawn from a vein, the skin surface is cleaned with antiseptic, and an elastic band (tourniquet) is placed around the upper arm to apply pressure and cause the veins to swell with blood. A needle is inserted into a vein (usually in the arm inside of the elbow or on the back of the hand) and blood is withdrawn and collected in a vial or syringe.
After the procedure, the elastic band is removed. Once the blood has been collected, the needle is removed and the area is covered with cotton or a bandage to stop the bleeding. Collecting blood for this test will only take a few minutes.
Either method (heel or vein withdrawal) of collecting a sample of blood is only temporarily uncomfortable and can feel like a quick pinprick. Afterward, there may be some mild bruising, which should go away in a few days.
The blood sample will be processed by a machine. The results are commonly available within a day or two. If results suggest an abnormality, the doctor may perform further tests.
This test is considered a safe procedure. However, as with many medical tests, some problems can occur with having blood drawn:
Having a blood test is relatively painless. Still, many children are afraid of needles. Explaining the test in terms your child might understand can help ease some of the fear.
Allow your child to ask the technician any questions he or she might have. Tell your child to try to relax during the procedure, as tense muscles can make it harder and more painful to draw blood. It also may help for your child to look away when the needle is being inserted into the skin.
If you have questions about the IgA test, speak with your doctor.
Reviewed by: Steven Dowshen, MD
Date reviewed: February 2011
|American Medical Association (AMA) The AMA has made a commitment to medicine by making doctors more accessible to their patients. Contact the AMA at: American Medical Association|
515 N. State St.
Chicago, IL 60610
|American Academy of Pediatrics (AAP) The AAP is committed to the health and well-being of infants, adolescents, and young adults. The website offers news articles and tips on health for families.|
|American Society of Hematology This group provides information relating to blood, blood-forming tissues, and blood diseases.|
|Arthritis Foundation The mission of this group is to support research to find the cure for and prevention of arthritis and to improve the quality of life for those affected by arthritis.|
|Lupus Foundation of America The mission of the Lupus Foundation of America is to educate and support those affected by lupus and find a cure. Call (800) 558-0121 for information.|
|Blood Test: C-Reactive Protein (CRP) A C-reactive protein (CRP) blood test is used to identify inflammation or infection in the body.|
|Blood Test: Erythrocyte Sedimentation Rate (ESR) An erythrocyte sedimentation rate test (ESR) detects inflammation that may be caused by infection, some cancers, and certain autoimmune diseases.|
|Blood Test: Immunoglobulins (IgA, IgG, IgM) Evaluated together, immunoglobulins (antibodies in the blood) can give doctors important information about immune system functioning, especially relating to infection or autoimmune disease.|
|Immune System The immune system, composed of special cells, proteins, tissues, and organs that protect against germs and microorganisms, is the body's defense against disease.|
|Blood Test (Video) This video shows what it's like to get a blood test.|
|Getting a Blood Test (Video) A blood test might sound scary, but it usually takes less than a minute. Watch what happens in this video for kids.|
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