Coeliac screen/ Tissue transglutaminase antibodies (TTg) IgA, TTG IgG
Coeliac disease is a gluten sensitive enteropathy affecting genetically-predisposed people (HLA DQ2/HLA DQ8) of all ages from infancy. Dermatitis herpetiformis (DH) is a blistering cutaneous manifestation of coeliac disease, these patients usually have mild gastrointestinal symptoms. DH is characterised by itchy vesicles on the forearms, elbows and buttocks. Coeliac disease is caused by an autoimmune reaction to dietary wheat gluten proteins (gliadin & glutenins) barley hordeins and rye secalins, following processing by the enzyme tissue transglutaminase (TTG).
Autoantibodies to gliadin, deamidated gliadin, tissue endomysium and TTG can be detected in patients with coeliac disease. Of these positive antibodies against tissue transglutaminase IgA subclass (TTGA) are highly specific and sensitive for the diagnosis of coeliac disease. The gold standard test for dermatitis herpetiformis diagnosis is direct immunofluorescence on skin biopsy, although TTG IgA is present in a high proportion of these patients.
In the paediatric population a TTG IgA result over 10x the upper limit of normal (i.e. >150 U/ml for our assay) together with a positive endomysium IgA result on two separate samples is sufficient to diagnose Coeliac disease without the requirement for a duodenal biopsy (ESPGHAN 2020).
This assay measures TTG IgA and IgG antibodies using a magnetic bead based fluoroenzymeimmunoassay. As IgA deficiency is found at higher frequency in this patient group the assay has the ability to detect low IgA levels and will automatically test for TTG IgG instead. Newly TTG IgA positive patients will further be tested for IgA endomysial antibodies by indirect immunofluorescence on primate tissue.
Suspected gluten sensitivity
Monitoring compliance with gluten-free diet
Unexplained iron, vitamin B12 or folate deficiency anaemia
Osteoporosis
Unexplained peripheral neuropathy
Chronic diarrhoea, differential diagnosis of irritable bowel syndrome (IBS) Failure to thrive in infants
Chronic fatigue
Testing is also recommended in at risk groups (type 1 diabetes, trisomy 21 syndrome, autoimmune thyroid and liver disease and first degree relatives of people with coeliac disease).
<15 U/mL
Reference ranges are manufacturer derived and were verified in house
This test is currently unaccredited due to a relocation of the analyser (no changes to assay used).
This test is not currently accredited
Record last updated
March 27, 2026
Sample Container
5ml SST Vacutainers (Rust top)
Search test database
Test Results
Yes, we have a Pathology User Guide
Yes. Please email your request to Imperial.nwlpcustomerservice@nhs.net
Results are communicated to clinical staff and are normally not communicated direct to patients either on telephone requests or in written report. If you need to contact us please click here to view the contact details page
Please contact the Customer Service Team Monday to Friday from 8:30am – 6:00pm on 0203 313 5353. Alternatively, see the Pathology User Guide for how to contact the relevant department. If advice is not urgent you can also email your query to Imperial.nwlpcustomerservice@nhs.net
Additional tests may be added by discussion with the relevant laboratory. The time limit for adding additional tests to a sample already received in the laboratory will depend on the type of sample and the department it was sent to.
Information on the repertoire of tests performed by pathology, including reference ranges, turnaround times and specimen requirements, can be found in the test directory.
Different tests have different sample stability requirements. If a comment on results indicates that the sample was delayed, the links below will indicate which tests may have been affected. This information is for serum or plasma samples.
For some tests, the impact of delay is consistent and these are marked with an arrow:
↑ indicates tests where delayed centrifugation results in falsely elevated results and the true level is likely lower than that reported.
↓ indicates tests where delayed centrifugation results in falsely lowered results and the true level is likely higher than that reported.
If there is no arrow, the true level may be lower or higher than reported.
Please interpret results with caution and consider the impact of any uncertainty.
The comment on the report will state how delayed the sample was. Please click the relevant link below to see which other tests may have been affected.
| >8h | >12h | >24h | >48h | >72h |
Phlebotomy services are not managed by NWLP. For further information please see:
Imperial College Healthcare Trust Phlebotomy services
Chelsea and Westminster Hospital NHS Foundation Trust Phlebotomy services
NWLP operates UKAS accredited medical laboratories as per the references below. The current scope of accreditation for all NWLP’s laboratories can be found on the UKAS website.
UKAS accredited medical laboratory/medical diagnostic service:
- Clinical Biochemistry No. 8673
- Haematology and Blood Transfusion No. 8674
- Infection & Immunity Sciences (Including Immunology, Virology, Microbiology and Histocompatibility and Immunogenetics ) No. 8659
- Cellular Pathology (Including Histopathology, Cytology and Molecular Pathology) No. 9615
If you require copies of our certificate of accreditation and associated documentation please contact Imperial.nwlpcustomerservice@nhs.net.
UKAS requires the laboratories to be accredited for a particular repertoire/scope (ISO15189), any changes or additions to repertoire require assessment by UKAS (extension to scope).
The BD Hospital Tube Guide, BD GP Tube Guide and BD Paediatric Tube Guide provide visual references to the correct tube types and collection instructions.
Home testing
INSTRUCTION SHEET FOR BLOOD SAMPLE COLLECTION
We also have two instruction videos available (one with subtitles and one without) – please click on the links to view the videos on Google.
Our accreditations
Upholding excellence in diagnostic standards
Our laboratories are accredited by the UK Accreditation Service (UKAS) against the international standard ISO15189:2022. UKAS is the accreditation body for the UK that assesses medical laboratories.
Find out more about our accreditations on the UKAS website.
UKAS website