There are specific blood tests used to diagnose coeliac disease. They look for antibodies that the body makes in response to eating gluten. Your GP will carry out a simple blood test to check for these antibodies.
In adults, with suspected coeliac disease, the following blood tests are recommended:
- Total immunoglobulin A (IgA)
- IgA Tissue transglutaminase antibody (shortened to tTG)
If IgA tTG is weakly positive then IgA endomysial antibodies (shortened to EMA) should be used.
In children with suspected coeliac disease, the following blood tests are recommended:
- Total IgA
- IgA tTG
It's important to continue eating gluten until you have had a blood test and gut biopsy. If you remove or reduce the amount of gluten in your diet before testing this will affect your result. Guidelines recommend that you eat some gluten in more than one meal every day for at least six weeks before testing.
It’s possible to have a negative blood test and still have coeliac disease. If you weren't eating gluten at the time of your blood test, you may have received an inaccurate result.
If you have ongoing symptoms that suggest coeliac disease but have had a negative blood test, ask your GP to check to see if you have been tested for IgA deficiency.
Some people with coeliac disease do not make the usual coeliac disease antibodies. This is called IgA deficiency. When the laboratory is measuring your antibody level they should also check your total serum IgA to detect IgA deficiency. If you are IgA deficient the following tests should be considered:
- Immunoglobulin G (IgG) EMA
- IgG deamidated gliadin peptide (DGP)
- IgG tTG
If you have tested negative for coeliac disease, particularly if you have Type 1 diabetes or you are a close relative of someone with coeliac disease, it is important to note that coeliac disease may present with a wide range of symptoms and you should consult with your GP if any symptoms arise or persist.
Read more about getting diagnosed.