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Allergy & Intolerance

Total IgA: why it is measured alongside the coeliac test anti-tTG IgA

According to the NVKC, antibodies made in your digestive tract are usually IgA antibodies. Antibodies are proteins of your immune system that clear away foreign substances and fight infections with viruses, bacteria or parasites, and total IgA is the amount of all IgA in your blood.

With an IgA deficiency, a coeliac test that measures IgA antibodies can be falsely negative, according to the NVKC. According to MedlinePlus, a raised IgA can fit a chronic infection, especially of the gastrointestinal tract, among other things. Only a blood test shows how much IgA you have.

Star-SHL gives 0.4 to 3.5 g/l as the reference values for total IgA in adults, and according to the NVKC an IgA deficiency is an IgA below 0.07 g/l.

Doctor's Assessment Included

IgA is an antibody, a protein that helps fight infections, found mainly in the stomach, the gut, saliva and breast milk. In the oldest age group of each of the four laboratories, the lower limit lies between 0.4 and 0.7 g/l and the upper limit between 3.5 and 4.0 g/l.

  • Total IgA is measured alongside the coeliac test anti-tTG IgA: with an IgA deficiency, that coeliac test can be falsely negative.
  • For children being tested for coeliac disease whose total IgA is low (low for their age, or below 0.2 g/l in children older than 3), the Dutch coeliac guideline advises a coeliac test based on IgG.
  • According to the NVKC, a slight rise in antibodies such as IgA is common during or just after an infection.

Total IgA: what Dutch laboratories use

There is no nationally agreed reference value; this is what individual laboratories publish.

The upper limit runs from 3.5 g/l at Star-shl to 4 g/l at Unilabs.

Reference ranges by group, in g/l
Star-shl · Everyone · 18 years and older 0.4–3.5 g/l
0.4 3.5
Unilabs · Everyone · 16 years and older 0.7–4.0 g/l
0.7 4
Certe · Everyone · 19 years and older 0.7–4.0 g/L
0.7 4
Diagnostiek voor U · Everyone · 16 years and older 0.4–3.5 g/L
0.4 3.5
0 4.4 g/l

Source: Star-shl

Source: Unilabs

Source: Certe

Source: Diagnostiek voor U

Each value as the laboratory itself publishes it, retrieved in 2026.

Total IgA: what this test measures

The total IgA test measures how much IgA is in your serum, in grams per litre (g/l). In a coeliac work-up, Unilabs starts with the coeliac test IgA-TTG; if that is not detectable, below 0.3 kU/l, and the measuring system detects no background noise, Unilabs measures total IgA, and with an unmeasurably low total IgA an IgG test (IgG-DPG) follows automatically.

Total IgA: why this value matters

According to the NVKC, total IgA is measured in coeliac screening together with anti-tTG IgA, IgA antibodies against tissue transglutaminase, so that a falsely negative anti-tTG IgA can be ruled out when IgA is deficient. According to Thuisarts, with coeliac disease a person becomes ill from gluten, a protein found in wheat, barley and rye among others, and gluten then causes inflammation in the gut. According to the NVKC, people with coeliac disease more often have an IgA deficiency.

Total IgA: how the blood test works

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Total IgA: when is testing worthwhile?

For coeliac screening, the NVKC advises requesting total IgA and anti-tTG IgA together. According to Unilabs, no gluten-free diet should be followed in the six weeks before that blood draw, because without gluten intake the coeliac test IgA-TTG can be falsely negative.

Total IgA: symptoms of a high or low value

Low Levels

According to the NVKC, a total IgA below 0.07 g/l counts as an IgA deficiency, and in testing for coeliac disease it is then usual, according to the NVKC, to also measure IgG antibodies against tissue transglutaminase. For children being tested for coeliac disease with a total IgA that is low for their age, or below 0.2 g/l once they are older than 3, the Dutch coeliac guideline advises a coeliac test based on IgG.

High Levels

According to MedlinePlus, a raised total IgA may fit chronic infections, especially of the gastrointestinal tract, inflammatory bowel diseases such as Crohn's disease or ulcerative colitis, and multiple myeloma, a type of bone marrow cancer. In a study of people with alcohol-related liver disease, published in the Canadian Liver Journal, about 70% had a raised IgA, but the IgA level there did not predict whether the liver disease progressed.

Total IgA: causes of a low or high value

What lowers the value

  • IgA deficiency without symptoms

    According to the NVKC, about 1 in 700 people has an IgA deficiency without symptoms.

  • Some medicines

    Medicines such as phenytoin and sulfasalazine can cause an IgA deficiency in some users.

  • Protein loss through the gut

    A gut disease that leads to protein loss can lower IgA.

What raises the value

  • Chronic infections, especially of the gut

    Chronic infections, especially of the stomach and gut, can raise IgA.

  • Inflammatory bowel disease

    Crohn's disease and ulcerative colitis can raise IgA.

  • Alcohol-related liver disease

    In a study of people with alcohol-related liver disease, IgA was raised in about 70 percent.

  • Multiple myeloma

    IgA can also be raised in multiple myeloma, a form of bone marrow cancer.

Total IgA: lifestyle and this value

An abnormal total IgA is one to discuss with your GP. In adults with an IgA deficiency and suspected coeliac disease, the Dutch coeliac guideline advises always taking duodenal biopsies, small pieces of tissue from the duodenum.

Total IgA: frequently asked questions

What is the difference between total IgA and anti-tTG IgA?

Total IgA is the amount of all IgA antibodies in the blood, and anti-tTG IgA are only the IgA antibodies against tissue transglutaminase, which according to the NVKC can be used in making the diagnosis of coeliac disease.

Can an IgA deficiency go away by itself?

Yes, according to MSD, a selective IgA deficiency goes away by itself in some people. According to MSD, some people with a selective IgA deficiency develop common variable immunodeficiency (CVID), another immune disorder, over time.

Are IgA reference values the same at every laboratory?

No, the reference values for total IgA differ between laboratories: Diagnostiek voor U gives an upper limit of 3.5 g/l from age 16 and Unilabs an upper limit of 4.00 g/l from age 16.

Total IgA: sources

  1. Star-shl, Labbepalingen (referentiewaarden per bepaling), star-shl.nl, geraadpleegd 2026-10-01 (retrieved 2026) star-shl.nl
  2. Unilabs, Bepalingenklapper (referentiewaarden per bepaling), bepalingenklapper.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenklapper.nl
  3. Certe, Bepalingenwijzer (referentiewaarden per bepaling), bepalingenwijzer.certe.nl, geraadpleegd 2026-10-01 (retrieved 2026) bepalingenwijzer.certe.nl
  4. Diagnostiek voor U, eLabgids (Referentiewaarden DvU), diagnostiek.getincontrol.eu, geraadpleegd 2026-10-01 (retrieved 2026) diagnostiek.getincontrol.eu
  5. NVKC, Zinnige Diagnostiek: coeliakie, 2015, geraadpleegd 2026-10-06 (retrieved 2026) nvkc.nl
  6. Fernandez J. Selective IgA Deficiency. MSD Manual Professional Version, October 2024. (retrieved 2026) msdmanuals.com
  7. MedlinePlus Medical Encyclopedia: Quantitative nephelometry test, review date 5/1/2026, consulted 2026-10-06. (retrieved 2026) medlineplus.gov
  8. Serum immunoglobulin A levels and alcohol-induced liver disease. Can Liver J 2020;3(2). (retrieved 2026) pmc.ncbi.nlm.nih.gov

Tests with related values

These panels measure values from the same category as this marker.

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Total IgA

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