Immunoglobulin A (IgA)
Also called: IgA, Immunoglobulin A, Total IgA
The main antibody protecting the body's surfaces — the gut, airways and other linings. Its most practical everyday use is a supporting one: a total IgA is checked when testing for coeliac disease, because the standard coeliac test can be falsely negative if IgA is low.
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What does Immunoglobulin A (IgA) measure?
Immunoglobulin A is the antibody class that guards the body's mucosal surfaces — the lining of the gut, the airways, and secretions like saliva and tears. Total IgA measures the overall amount in the blood. Its most common practical role is not as a headline test but as a check that makes another test reliable: the standard blood test for coeliac disease measures an IgA-type antibody (tissue transglutaminase IgA), so if a person is deficient in IgA — which is the commonest primary immune deficiency, present in about 1 in 500 people — that coeliac test can read falsely negative and miss the diagnosis. Checking total IgA alongside flags this and prompts an alternative test. Beyond that, a low IgA (selective IgA deficiency) is often harmless but can associate with recurrent infections and autoimmune conditions, while a high IgA can be seen in chronic infections, liver disease and IgA-related kidney disease.
What does a high Immunoglobulin A (IgA) level mean?
- Chronic infections or inflammation — a non-specific rise.
- Liver disease (especially alcohol-related cirrhosis).
- IgA nephropathy — a common kidney condition involving IgA.
- Some blood conditions (IgA myeloma) — a marked, clonal rise, uncommon.
What does a low Immunoglobulin A (IgA) level mean?
- Selective IgA deficiency — the commonest primary immune deficiency (~1 in 500); often harmless but important because it makes the standard coeliac blood test unreliable.
- Association with recurrent infections and autoimmune disease — in a minority.
- A low IgA is the key reason to interpret coeliac serology with care and use an alternative test if needed.
When to discuss with a doctor
The single most useful reason to check total IgA is when testing for coeliac disease: because the standard test is IgA-based, a low total IgA means that test can be falsely negative, and an alternative (IgG-based) test should be used instead. Beyond that, a low IgA found incidentally is often harmless and simply noted, though recurrent infections or autoimmune symptoms would prompt further immune assessment. A markedly high IgA is interpreted in the context of liver, kidney or, rarely, blood conditions. Mediora.AI shows total IgA alongside coeliac and immune markers so results are read correctly — especially flagging when a low IgA could undermine a coeliac test; the interpretation belongs with your doctor.
Related markers
Commonly confused with
- Immunoglobulin G (IgG) Both are immunoglobulins, but they work in different places. IgA guards the surfaces - gut, airways, saliva. IgG circulates in the blood and carries long-term memory of past infections and vaccinations.