Tissue transglutaminase antibodies
| Category | Immunology |
|---|---|
| Test background |
Coeliac disease is an autoimmune disorder of the small intestine that occurs in genetically-predisposed people of all ages from infancy. It is caused by a reaction to gliadin, a gluten protein found in wheat. Upon exposure to gliadin, the enzyme tissue transglutaminase (tTg) modifies this protein and the immune system cross-reacts with the bowel tissue, causing an inflammatory reaction. Positive antibodies against tissue transglutaminase are highly specific and sensitive for the diagnosis of coeliac disease. These are of the IgA isotype, however IgA deficiency is common in this group of patients, and those that are IgA deficient will be tested for anti tTg-IgG antibodies. |
| Clinical Indications |
Suspected gluten sensitivity (this test is specific for coeliac disease, but a jejunal biopsy is recommended for confirmation), chronic diarrhoea, failure to thrive and fatigue. Can also be used to monitor compliance with gluten-free diet. Testing is also recommended in at risk groups (type 1 diabetes, Downs syndrome, autoimmune thyroid disease and first degree relatives of people with coeliac disease). |
| Reference range | <15 U/mL |
| Sample & container required | RST (rust top) |
| Sample volume | 5-10 mL (1 mL serum) |
| Turnaround time | 7 days |
| Notes | If excluding coeliac disease, patient should be on a gluten containing diet for antibody (blood) testing to be accurate. |