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Doctor's Assessment Included

Every result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.

Autoimmune

Immunoglobulin IgA: what the blood test measures

IgA testing evaluates mucosal immunity and validates coeliac screening results. For women, IgA deficiency is associated with higher rates of autoimmune conditions.

What It Measures

This test measures how much immunoglobulin A is present in your blood. IgA is produced by immune cells in mucosal tissue. It protects body surfaces that are exposed to the outside environment, such as the gut and airways. An immunoglobulins test may be part of a broader look at the immune system.

Why It Matters

IgA deficiency affects approximately 1 in 500 people and may be associated with recurrent respiratory and gastrointestinal infections. IgA levels must also be adequate for coeliac disease antibody tests (anti-TTG, endomysium) to be reliable, and IgA levels are also relevant when screening for autoimmune diseases of the gut.

When to Test

Testing could be indicated for recurrent sinopulmonary or gastrointestinal infections, suspected immunodeficiency, alongside coeliac disease testing (to validate IgA-based tests), or evaluation of IgA nephropathy.

Symptoms

Low Levels

Low IgA may be associated with frequent infections such as sinusitis, pneumonia and gastrointestinal infections. It can also be linked to autoimmune disorders and allergies. Many people with low IgA have no symptoms at all.

High Levels

Elevated IgA may be associated with chronic infections, IgA nephropathy, liver disease (particularly alcohol related) or inflammatory bowel disease. In rare cases it can point to IgA myeloma. A doctor always interprets the result in the context of your symptoms.

Lifestyle Tips

If IgA deficiency is confirmed, discuss vaccination strategies and infection prevention with your healthcare provider. Wear a medical alert bracelet, as IgA-deficient people may have transfusion reactions to IgA-containing blood products.

Every blood test result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.

Frequently Asked Questions

Why test IgA with coeliac disease screening?
Anti-TTG and endomysium tests are IgA-based. If you are IgA deficient, these tests may give false-negative results. IgG-based alternatives must be used instead.
Is IgA deficiency treatable?
There is no specific treatment to replace IgA. Management focuses on prompt treatment of infections and awareness of the condition.
Can IgA deficiency cause blood transfusion problems?
Yes. Some IgA-deficient patients develop anti-IgA antibodies, which can cause anaphylactic transfusion reactions. Washed or IgA-depleted blood products may be needed.