What is the blood test for Celiac Disease & range?

A simple blood test is available to screen for celiac disease. The blood test tests the antibodies in the body.

People with celiac disease who eat gluten have higher than normal levels of certain antibodies in their blood. These antibodies are produced by the immune system because it views gluten (the proteins found in wheat, rye and barley) as a threat. You must be on a gluten-containing diet for antibody (blood) testing to be accurate.

For most children and adults, the best way to screen for celiac disease is with the Tissue Transglutaminase IgA antibody, plus an IgA antibody in order to ensure that the patient generates enough of this antibody to render the celiac disease test accurate. You may see the test name expressed in this way a lot – tTG-IgA.

tTG-IgA

The tTG-IgA test will be positive in about 98% of patients with celiac disease who are on a gluten-containing diet. The same test will come back negative in about 95% of healthy people without celiac disease. The test is sensitive.

For young children (around age 2 years or below), Deamidated Gliadin IgA and IgG antibodies should also be included. All celiac disease blood tests require that you be on a gluten-containing diet to be accurate.

The reference value of tTG-IgA is:

  • <4.0 U/mL (negative)
  • 4.0-10.0  U/mL (weak positive)
  • >10.0 U/mL (positive)

Reference values apply to all ages.

The finding of tissue transglutaminase (tTG)-IgA antibodies is specific for celiac disease and possibly for dermatitis herpetiformis. For individuals with moderately to strongly positive results, a diagnosis of celiac disease is likely and the patient should undergo biopsy to confirm the diagnosis.

If patients strictly adhere to a gluten-free diet, the unit value of IgA-anti-tTG should begin to decrease within 6 to 12 months of onset of dietary therapy.

Other tests

There are other tests available but less commonly used.

  • IgA Endomysial antibody (EMA)
  • Total serum IgA
  • Deaminated gliadin peptide (DGP IgA and IgG)

 

Genetic testing

People with celiac disease carry one or both of the HLA DQ2 and DQ8 genes, but so does up to 25-30% of the general population. Carrying HLA DQ2 and/or DQ8 is not a diagnosis of celiac disease nor does it mean you will ever develop celiac disease. However, if you carry HLA DQ2 and/or DQ8, your risk of developing celiac disease is 3% instead of the general population risk of 1%.

 

* The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.