Tissue Transglutaminase (TTG)

Department of Immunology

Indication

Highly sensitive and specific test for coeliac disease or dermatitis herpetiformis.

Notes

• This assay is used as a primary screen for coeliac disease. Confirmatory IgA anti-endomysial (AEA) is performed on all positives.
• AEA will not be performed independently of TTG.
• The assay has a built-in check for detectable IgA, and when low serum immunoglobulins will also be measured. If IgA<0.2g/L the sample will be referred for IgG endomysial antibodies.
• In children, with a TTG >100 this is highly suggestive of coeliac disease (so a biopsy may not be necessary).
• TTG requests will not routinely be processed within a year of a previous negative TTG.
• Serological assays for the investigation of Coeliac disease are only accurate if the patient is on a gluten - containing diet, e.g., gluten in more than 1 meal per day, for at least 6 weeks prior to testing.

Sample Requirements

Adult

5ml Gold-top SST tube or 3.5ml Rust-top gel tube (Trust users only)

Paediatric

1ml Serum Sample

Turnaround Times

7 days

Time Limit for Add-ons

2 weeks (whilst stored at 2°C - 8 °C)