What is IgA?
Antibodies come in five kinds, and IgA is the kind your body sends outward. It is made by immune cells just beneath your mucous membranes and secreted into the layer of mucus on your gut wall, in your airways, in saliva, tears and breast milk. There it intercepts bacteria and viruses before they enter your tissue: a border guard, where IgG in the blood is the domestic police. Some IgA also circulates in the blood, and that part is what this test measures. It is a sum of all your IgA, regardless of what it is directed against; that is different from an IgA antibody against one target, such as the coeliac test, which measures IgA against a gut enzyme and has its own numbers. Your report shows IgA in g/L. Normal for an adult is 0.7 to 3.5 g/L, where the labs overlap; the range still rises in the teenage years and differs slightly per lab at both ends.
Why is IgA relevant?
IgA is measured for two reasons, and the first is the coeliac test. That test measures an IgA antibody, and anyone who makes little or no IgA themselves always tests negative on it, even with coeliac disease. That is why total IgA belongs as standard beside the coeliac test: it says whether the test could measure anything at all. An IgA deficiency occurs in about one in six hundred people, and precisely those people have an increased chance of coeliac disease. The second reason is the immune system itself. An IgA deficiency is the most common inborn immune deficiency, and most people notice nothing of it; some have more frequent airway and gut infections, allergies or autoimmune diseases. Anyone who keeps catching colds or getting sinus infections often has IgA determined together with IgG and IgM to see whether the immune system is complete. A high IgA has little to do with the immune system and a lot with lasting stimulation. Alcohol is the best-known cause: the liver clears IgA, and with heavy drinking and with a fatty or diseased liver it accumulates. Chronic infections and inflammations, of the gut, the airways or the gums, do the same. For anyone who wants to stay healthy a high IgA is therefore more often a question about alcohol and the liver than about the immune system.
IgA reference ranges
What counts beside the number:
- The coeliac test, which can only be read if your IgA is normal
- IgG and IgM, the other two antibody classes; together they show whether the immune system is complete
- Your alcohol use and the liver values, the first look with a high value
- An inflammation or infection you know of: gut, airways, gums
- How often you have infections, with a low value
- Medicines that suppress the immune system
The band above is where the labs overlap; the range on your own report may be slightly wider, and there is no national normal value. In coeliac investigation total IgA belongs as standard beside the coeliac test: anyone who makes too little IgA always tests negative on it and has an increased chance of coeliac disease. One lab does not run total IgA and publishes only IgA tests against individual targets.
What Dutch labs actually use
Three labs publish a reference value for IgA. Unilabs does not carry the determination, so this page sets three tables side by side instead of four. For IgG and IgM the three labs print exactly the same adult figures. For IgA they do not, and they part at both ends. Star-shl starts at 0.4 g/L where Certe and Clinical Diagnostics only start at 0.7, and Star-shl stops at 3.5 where those two run on to 4. Where the three overlap, an adult from 19 yrs is left with 0.7 to 3.5 g/L: the floor comes from Certe and Clinical Diagnostics, the ceiling from Star-shl. A result of 0.5 g/L therefore falls inside the band at Star-shl and below it at the other two, and 3.8 g/L falls above it at Star-shl and inside it at the other two.
0.7 – 3.5g/L
Between 0.4 and 0.7 and between 3.5 and 4.00 it depends on the lab, because each sets its limits on its own method and population. Above 4.00 every lab calls it abnormal.
every lab calls 0.7 – 3.5 g/L normal. Between 0.4 and 0.7 and between 3.5 and 4.00 it depends on the lab.
Every age, per lab
| Laboratory | Group | Reference range |
|---|---|---|
| Star-shl2026 | Adults | 0.4–3.5 g/L |
| Certe2026 | 14 to 19 yrs | 0.4–2.93 g/L |
| From 19 yrs | 0.7–4 g/L | |
| Clinical Diagnostics2026 | Adults | 0.7–4.00 g/L |
Each band as the lab publishes it, retrieved in 2026, unless marked otherwise.
IgA high or low: what it means
A high IgA comes, in order of how often it occurs, from: plenty of alcohol and a fatty or diseased liver, a lasting infection or inflammation of gut, airways or gums, autoimmune diseases such as rheumatoid arthritis, and rarely a kidney disease based on IgA or a proliferation of the cells that make IgA. With a high value the liver values and your alcohol use are the first look, and an inflammation you know of the second. A low IgA is usually inborn and harmless: an IgA deficiency you notice nothing of, which does mean the coeliac test needs a different approach in you. Some people with a deficiency have more frequent infections or allergies. More rarely a low IgA is acquired: from medicines that suppress the immune system, from protein loss through the kidneys or the gut, or as part of a broader immune deficiency in which IgG is low too. What you do about it: an inborn deficiency cannot be fixed and usually needs nothing, except knowing you have it. A high IgA from alcohol falls when the drinking stops and the liver recovers; with a chronic inflammation it falls when that settles. For mucosal immunity in general, sleep, not smoking and a healthy gut count more than any supplement. Read IgA beside IgG and IgM, the other two large antibody classes, beside the liver values with a high value, and always beside the coeliac test if that was done.
What lowers it
Usually inborn and harmless; rarely acquired.
| Cause | How often |
|---|---|
| An IgA deficiencyThe most common inborn immune deficiency, in about one in six hundred people; usually without complaints, sometimes with more frequent infections or allergies, and always relevant to the coeliac test | Sometimes |
| Medicines that suppress the immune systemPrednisone, methotrexate and other immunosuppressants lower antibody production, usually together with IgG | Sometimes |
| Protein loss through kidneys or gutWith a leaking kidney filter or a gut that loses protein, antibodies are lost with it | Rare |
What raises it
Lasting stimulation: alcohol, the liver, a chronic infection or inflammation.
| Cause | How often |
|---|---|
| Plenty of alcohol or a liver diseaseThe liver clears IgA; with heavy drinking and with a fatty or diseased liver it accumulates, and it falls again as the liver recovers | Often |
| Lasting inflammation or infectionA chronic infection or inflammation of gut, airways or gums stimulates mucosal immunity into more IgA | Sometimes |
| Autoimmune diseasesRheumatoid arthritis and other autoimmune diseases raise IgA along with the inflammation | Sometimes |
| A proliferation of antibody cellsRare: a strongly raised IgA of one kind fits a plasma cell disorder, and then further investigation is needed | Rare |
How does an IgA blood test work?
- Referral
- Not needed. Ask for total IgA, because IgA tests against one target also exist, such as the coeliac test, with their own numbers.
- Fasting
- Not needed.
- The draw
- One tube of blood from a vein in your arm, usually together with IgG and IgM, and in coeliac investigation with the coeliac test.
- The result
- A single number in g/L. Usually available within a few days.
- Repeating
- An inborn deficiency does not change and does not need following. A high IgA from alcohol or inflammation again after a few months, once the cause has been addressed.
- Where to draw
- You can draw at 250+ locations near you, no referral needed. See the locations
Frequently asked questions
What is IgA?
Immunoglobulin A is the antibody that guards your mucous membranes: your gut, your airways, your saliva and your tears, the places where your body meets the outside world. It intercepts bacteria and viruses before they enter your tissue. This test adds up all your IgA in the blood, regardless of what it is directed against.
What is a normal IgA level?
From age 19, 0.7 to 3.5 g/L, where the labs overlap; the range on your own report may be slightly wider at both ends. In the teenage years it is still lower and rises to the adult level.
What does a low IgA mean?
Usually an inborn IgA deficiency, the most common immune deficiency, in about one in six hundred people. Most people notice nothing of it; some have more frequent airway or gut infections, allergies or autoimmune diseases. The most important consequence is that the coeliac test always comes out negative in you, while the chance of coeliac disease is actually increased; then another antibody is measured. Rarely a low IgA is acquired, from immunosuppressant medicines or protein loss.
What does a high IgA mean?
Usually lasting stimulation. Alcohol is the best-known cause: the liver clears IgA, and with heavy drinking or a fatty or diseased liver it accumulates. Chronic infections and inflammations of gut, airways or gums, and autoimmune diseases do the same. Rarely a strongly raised IgA fits a kidney disease or a proliferation of antibody cells. With a high value your alcohol use and the liver values are the first look.
Why does total IgA belong with a coeliac test?
Because the coeliac test measures an IgA antibody. Anyone who makes too little IgA always tests negative on it, even with coeliac disease, and precisely people with an IgA deficiency have an increased chance of coeliac disease. Total IgA therefore says whether the test could measure anything; with a deficiency an IgG variant of the test is used.
Can I raise my IgA?
Not an inborn deficiency; that is a trait, not a shortage you top up. What does mucosal immunity in general good is enough sleep, not smoking, a healthy gut with plenty of fibre, and no supplements that promise to boost the immune system. A high IgA you lower by removing the cause: less alcohol, letting the liver recover, treating an inflammation.
What is the difference with IgG and IgM?
They are three classes of antibodies with their own task: IgM comes first with a new infection, IgG takes over and stays in the blood longest, IgA guards the mucous membranes. With recurring infections they are measured together to see whether the immune system is complete.
Do I need to fast?
No. Do ask for total IgA and not for an IgA test against one target, because those have their own numbers.
Which tests include IgA?
IgA is part of Advanced, the broader panel. It is not orderable yet.
Related biomarkers
Sources
- 1.Star-shl, test catalogue (Dutch): immunoglobulin IgA, IgG, IgM. 2026. star-shl.nl
- 2.Certe, test catalogue (Dutch): total IgA. 2026. bepalingenwijzer.certe.nl
- 3.LESA Laboratory diagnostics (Dutch primary-care laboratory agreement). 2026. richtlijnen.nhg.org
- 4.Clinical Diagnostics, lab guide (Dutch): IgA. 2026. clinicaldiagnostics.nl
Educational information only, not medical advice. Consult a healthcare professional for clinical decisions.
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IgA is part of Advanced, the broader panel. It is not orderable yet.
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