No popular authors found.
Ads by Google:

Categories

No categories found.


Get Celiac.com's E-Newsletter




Ads by Google:


Questions? Join Our Forum:
~1 Million Posts
& Over 66,000 Members!



SHARE THIS PAGE:
Celiac.com Sponsors:

Tests for IgA Antibodies to Tissue Transglutaminase Vary Too Much For Easy Commutability

Celiac.com 08/26/2015 - People with IgA antibodies to tissue transglutaminase (anti-tTg) likely have a higher risk for celiac disease. Some clinicians and researchers have suggested that common multiples of the upper limit of normal (ULN) be useful tool in improving diagnostic pathways, as well as continuity between tests.

Photo: CC--Alexandre DulaunoyHowever, a new study suggests that both sensitivity and specificity of tests for IgA antibodies to tissue transglutaminase vary widely by individual kit, and that their test values are not easily commutable using common multiples of the ULN to correct for inter-assay variations. Commutability just means the ability to make sure that two different tests really are equal. If results of different tests are commutable, it means that they are equal. In this case, the term applies to test results for various representative samples from healthy and diseased individuals.

For the study, the research team recently looked at the use of immunoassays for the detection of IgA antibodies to tissue transglutaminase, and also sought to better understand of the significance of multiples of the upper limit of normal and inter-assay correlations. The research team included B.B. Suh-Lailam, K.W. Davis, and A.E. Tebo. Using indirect immunofluorescence assay (IFA) as reference, the team assessed characteristics of four anti-tTG IgA assays relative to endomysial IgA (EMA).

They also assessed commutability between anti-tTG immunoassays and/or EMA based on manufacturer's recommended cut-off values and three common multiples of ULN (3×, 5× and 10×). To do this, they analyzed samples from 200 patients and 100 healthy individuals.

Ads by Google:

They found that, at manufacturer's cut-off, the sensitivities for the tTG assays ranged from 72.5% to 98.6% and specificities from 60.3% to 99.2%. The percent positive agreements between any anti-tTG and EMA or any two anti-tTG immunoassays varied from 56.7% to 98.0% and 46.7% to 100.0%, respectively.

At 3×, 5× or 10× ULNs, the inter-rater reliability as measured by Cohen κ between any two anti-tTG assays were quite variable and ranged from 0.28 to 0.96, 0.26 to 0.89 or 0.13 to 0.78, respectively.

Furthermore, the percent positive agreements between any two anti-tTg IgA immunoassays ranged from 83.1% to 98.2%, 92.0% to 100%, or 100%, at 3×, 5× or 10×, respectively.

Hence, the team's basic takeaway that result parameters for tTG IgA immunoassays or tTG IgA and EMA vary by kit, and thus common multiples of the ULN are not enough to correct for variation between tests.

Source:

Celiac.com welcomes your comments below (registration is NOT required).












Related Articles



Comments




Rate this article and leave a comment:
Rating: * Poor Excellent
Your Name *: Email (private) *:




In Celiac.com's Forum Now:


I would stick to a very basic gluten-free diet as recommended by Dr. Fasano and other celiac experts. It would not hurt for a short amount of time and might get him through his exams. This is the study about dealing with Trace Amounts of Hidden Gluten (not saying your son has non-responsi...

Yes do follow up with testing, once confirmed we can help you along the road. Other intolerance and allergies are very common with this disease. Lactose is broken down by enzymes produced by the tips of your villi in your intestines, they are normally the most damaged and in some cases just gone....

Please follow the advice of celiac experts and get your daughter tested before going gluten free, Your doctor, like many, is woefully misinformed. You should be tested too (all first degree relatives), even if symptom free, and especially since your mother was recently diagnosed. Learn more a...

We in the UK he takes a pack lunch and have asked for a health plan so wait and see. Not easy when he taking his gcse and he wants to do well. Thanks for the advice

My daughter, who does not have celiac disease, is also in the 11th grade. Since you said exams instead of finals, I assume you are not in the US where a 504 plan can accommodate anyone with a disability (celiac disease counts). This includes tudors, more time to complete tests, etc. Do you hav...