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  PTD-208 

Test Directory -  Coeliac Screen

Synonyms

 

tTG, tissue transglutaminase, anti gliadin antibodies, anti-endomysial antibodies

Clinical Indications

 

Coeliac Disease
Dermatitis herpetiformis
Please note: The anti tTG IgA assay should not be considered diagnostic, but should be used in conjunction with all clinical and laboratory findings.
Samples found to be tTG IgA positive or equivocal will be tested for the presence of anti endomysial IgA for confirmation as per recent guidelines.

Test Includes

Detection of IgA autoantibodies against tissue Transglutaminase. This is the primary Coeliac Disease screening test and requests for anti- endomysial or anti-gliadin antibodies will be screened for the presence of anti tTG IgA.

Request Form

Combined Pathology Blood form (Yellow/Black)

Availability

Analysed by referral laboratory

 

Specific criteria

 

None

 

Patient preparation

 

None required

 

Limitations

 

IgA tTG antibody will be negative in IgA deficient individuals (as will the IgA anti gliadin antibody and IgA endomysial antibody). IgG tTG will be assayed in these cases.

Turnaround Time

2 weeks

Specimen

Serum

Volume

2 ml

Container

Yellow top (SST) tube or

paediatric brown top

Causes for Rejection

 

Assay within previous 3 months

Reference range

 

Negative: less than 7.1 U/mL
Equivocal: 7.1 - 10.0 U/mL
Positive: greater than 10.0 U/mL

Interpretation

IgA tTG antibody provide the most sensitive (~90%) and specific (96%) marker for coeliac disease. IgA deficient patients are further tested for IgG tTG to confirm or rule out coeliac disease.

Lab handling

 

Processing: Immunology at the Hub laboratory


Version 1.1 / Feb 2016                                                                                                                Approved by: Consultant Biochemist