What it measures
IgA antibodies against tissue transglutaminase, an enzyme in the gut lining. People with coeliac disease make these antibodies when they eat gluten. It is the usual first blood test for coeliac disease.
Why people test it
- The usual first blood test when coeliac disease is suspected.
- Investigating symptoms such as bloating, diarrhoea, weight loss or tiredness.
- Checking for coeliac disease in people with iron deficiency anaemia, type 1 diabetes or a family history.
- Checking antibody levels in people with coeliac disease who follow a gluten-free diet.
Typical range
Results are given as a number against the lab's cut-off, which depends on the test kit the lab uses. Ranges vary by lab and method, and your report shows the lab's own cut-off. The test is usually read with total IgA, as low IgA can make it read falsely negative.
Finger-prick or vein?
A finger-prick sample is usually fine for an antibody test like this, and some providers offer a home kit. Others take blood from a vein, at a clinic or with a visiting nurse.
Avoiding gluten before the test can give an inaccurate result, as these antibodies are made in response to gluten in the diet.