Diagnostic Use
Coeliac disease is an immune mediated enteropathy triggered by dietary gluten. It is characterised by inflammation and villous atrophy of the small intestinal mucosa, which may result in malabsorption, diarrhoea and weight loss. Clinical presentations range from classical gastrointestinal symptoms to manifestations such as iron deficiency, osteoporosis and dermatitis herpetiformis.
Interpretation
Testing includes IgA tissue transglutaminase (tTG IgA) and IgG deamidated gliadin peptide (DGP IgG) antibodies. tTG IgA is the preferred serological test for coeliac disease, while DGP IgG is particularly useful in patients with IgA deficiency. Diagnostic testing should be performed while the patient is consuming a gluten containing diet. Antibody concentrations may be useful in monitoring adherence to a gluten free diet but should be interpreted in conjunction with the clinical context.
Positive antibody results support the diagnosis of coeliac disease but are not diagnostic in isolation. In adults, diagnosis is usually confirmed by endoscopic small bowel biopsy. For paediatric patients, please refer to current ESPGHAN guidelines (see below).
Reference Intervals
tTG IgA (tissue transglutaminase)
| <20 CU |
Negative |
| 20-30 CU |
Low positive |
| >30 CU |
Positive |
DGP IgG (demidated gliadin peptide)
| <20 CU |
Negative |
| 20-30 CU |
Low positive |
| >30 CU |
Positive |
Test Method
Methodology: Chemiluminescent immunoassay
Platform: Bio-Flash, INOVA Diagnostics Inc.
Limitations / Interference
Grossly haemolysed, icteric, microbially contaminated, heat treated, or specimens containing visible particles.
Uncertainty of Measurement
This information is available upon request.