Selective IgA Deficiency and the Blood Test To Detect It

IgA antibody
What is selective IgA deficiency?. Stocktrek Images/Getty Images

Selective IgA deficiency is the most common problem found in peoples' immune systems. It's especially common in people who have celiac disease -- they are about 10 to 15 times more likely than others to have IgA deficiency.

So what is it? Well, IgA stands for "immunoglobulin A," which is an antibody (i.e., a part of your immune system). This antibody helps your body fight off threats from toxins, bacteria and viruses.

Most people with selective IgA deficiency don't realize it, and don't show any obvious symptoms. However, they're more likely to suffer from frequent bouts with bronchitis, chronic diarrhea, eye infections, middle ear infections, pneumonia and sinusitis.

If you have selective IgA deficiency, some celiac disease blood tests used to screen for the condition won't produce accurate results.

How Can You Find Out If You Have IgA Deficiency?

Doctors can test for the condition. In fact, many doctors will test your IgA levels as part of overall celiac disease testing, because (as I said above) you won't get accurate celiac test results if you have low levels of IgA.

That's because several of the typically used celiac blood tests, including the AGA-IgA, tTG-IgA and the EMA-IgA, all depend on your having normal amounts of IgA in your blood stream. If you don't have enough IgA, these tests could come back negative even if you do actually have celiac disease.

If you're IgA-deficient, your physician will rely more on the results of your AGA-IgG blood test to determine whether you should undergo an endoscopy to diagnose celiac disease.

What Else Do I Need To Know About Selective IgA Deficiency?

Selective IgA deficiency is most common in people who are Caucasian — about one in every 500 Caucasians has IgA deficiency.

Most cases are inherited, although in a few instances,  a few cases of drug-induced selective IgA deficiency have been reported.

Since the condition involves a problem with your immune system, it does make you more likely to suffer from various illnesses. However, not everyone with selective IgA deficiency will catch all the bugs that are going around — other factors in your immune system could help to prevent this.

People with selective IgA deficiency are more prone than the general population to allergies and asthma. Also, in addition to celiac disease, other so-called autoimmune diseases, including rheumatoid arthritis and lupus, are more common in people with selective IgA deficiency.

There's currently no treatment for selective IgA deficiency. People with the condition who tend to suffer from frequent colds or infections may need to stay on antibiotics longer than usual. 

Sources:

Celiac Disease Frequently Asked Questions. University of Maryland Center for Celiac Research. Accessed Feb. 14, 2011.

Selective Deficiency of IgA. PubMed Health. Accessed Feb. 14, 2011.

Selective IgA Deficiency. Immune Deficiency Foundation. Accessed Sept. 30, 2015.

Serologic and Genetic Testing. Celiac Disease Center at Columbia University. Accessed Feb. 14, 2011.

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