IgA (Immunoglobulin A)
IgA is found where the body meets the outside world: the lining of the gut and airways, and in saliva and tears. It makes up roughly 10 to 15 per cent of the antibodies in blood. Selective IgA deficiency is the most common primary immune deficiency, affecting about one in six hundred people. Many have no symptoms at all, but it matters for one practical reason: the standard coeliac blood test is IgA-based and can be falsely negative in someone with IgA deficiency.
Why Test Immunoglobulin A?
The test is used when a primary immune deficiency is suspected, particularly with recurrent infections of the sinuses, airways or gut, and alongside coeliac testing so that a negative result can be interpreted correctly. It is also used to follow known immune deficiency.
What Do High Immunoglobulin A Levels Mean?
A raised IgA is seen with ongoing infection, chronic inflammation, liver disease, and in some autoimmune conditions. A markedly raised value can, rarely, indicate a blood disorder producing a single antibody type, and would then be investigated further.
What Do Low Immunoglobulin A Levels Mean?
A low IgA most often reflects selective IgA deficiency, which is usually harmless in itself but means the standard coeliac blood test cannot be relied upon: an alternative IgG-based test is used instead. Low IgA also occurs with certain medicines, including corticosteroids and immunosuppressants, and with conditions causing protein loss. If IgA is low alongside low IgG, a wider immune assessment is needed.
Symptoms to Watch For
- Recurrent infections of the sinuses, airways or gut
- Persistent diarrhoea or other gut symptoms
- Unintended weight loss
- Recurrent fevers
- Symptoms suggesting coeliac disease despite a negative test
Who Should Get Tested?
- People with recurrent infections of the airways or gut
- People being tested for coeliac disease, so a negative result can be interpreted
- Children with frequent infections
- People being followed for a known immune deficiency
How to Prepare for Your Test
No special preparation is needed. Bring valid ID to your appointment.
Order Your Blood Test
Test your Immunoglobulin A levels with an accredited Swedish laboratory. Results within days, reviewed by Wellth.
Frequently Asked Questions
Why does IgA matter for coeliac testing?
Is IgA deficiency serious?
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Wellth Team
Wellth
Our content is written and reviewed by Wellth, and fact-checked against peer-reviewed research and current Swedish clinical guidelines.
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The information on this page is provided for informational purposes only and does not constitute professional medical advice, diagnosis, or treatment. Wellth provides health information and testing services but is not a substitute for clinical care. Always consult a qualified healthcare provider if you have questions about a medical condition. If you are experiencing severe or urgent symptoms, contact your doctor or call 1177 Vårdguiden. Blood test results should be interpreted by a qualified healthcare professional in the context of your complete medical history.