TTG IGA and IGG interpretation help and further testing

[ceea44]

Hi there, I've been on a gluten free diet for over 10 years. Symptoms dramatically improved since then. At the time there was no blood test available to me for celiac diagnosis so my physician just advised me to treat it as if I did have celiac disease. Ten plus years later, I wanted to know if I could ease up with how strict I treat this diet so my new PCP said we could do a tissue transglutimase IgA and IgG. I questioned this as I was under the impression the results would not be accurate on a gluten free diet but she said they would still be accurate. I do not trust this provider's knowledge. IgA was normal < 2 and IgG was mildly high at 6 (0-5 is normal). She says endoscopy is the next step. I am happy to just remain on my gluten free diet but are there any other tests to help elucidate if I truly have a celiac diagnosis while I remain on my gluten-free diet?

Thanks in advance. 

[trents]

https://pubmed.ncbi.nlm.nih.gov/25925933/

The IGG was one of the first celiac disease tests developed. It came along in the 1980's. It is only about 80% accurate, and I take that to refer to it's specificity. The tTG-IGA is 98% specific for celiac disease. For all of these antibody and gliadin tests you would need to have been consuming gluten regularly for weeks or months in order for them to give valid results.

Edited April 26, 2023 by trents

[patty-maguire]

As Trents said, you do need to be consuming gluten for the tests to be accurate.  They measure the antibodies in your blood.  If the trigger (gluten) is not present there would be no antibodies.  Same goes for the scope.  After 10 years gluten free, any intestinal damage would likely be healed, so the scope would not be accurate.  

As for whether you can ease up on the diet...if you had been diagnosed with celiac the answer would be a resounding "NO", but you have not.  

It's common for doctors to recommend a "gluten challenge" for people who have tried a gluten free diet with some success and would like to be tested for celiac.  The classic gluten challenge is 4-6 slices of bread for 6-8 weeks then have the blood test done.  Some people find this amount of gluten intolerable so there is a modified gluten challenge which is 1.5 slices of bread for 2-4 week.  For the most part that seems to be enough to trigger a positive result. 

Another approach would be to have genetic testing done before getting into the gluten challenge.  Two gene variants, HLA DQ2 and DQ8 are connect with increased risk of celiac disease.  The presence of these genes does not mean you have celiac, but if you don't have the genes then it is highly unlikely you have celiac and you can save yourself the trouble of doing a gluten challenge and going through further testing.  You can ask your doctor about genetic testing or 23andMe does it. 

[Scott Adams]

It is strange that you were told 10 years ago that blood tests for celiac disease were not available. As @trents mentioned they've been around for decades, and the tTG tests that are most commonly used now have been widely available since the early 2000's. In any case, here is more info on the gluten challenge in case you get re-tested: