Celiac disease blood test

This is kind of OT, but I know there are a few of you here with celiac disease. Does anyone know for the celiac disease blood test (TTG) whether you have to eat gluten before getting it and, if so, for how long?

I've been having stomach issues lately and my GI ordered this test along with a bunch of others. I'm pretty sure it's not celiac based on 1) having an endoscopy a year and a half ago that had a normal biopsy (although the doctor wasn't looking for celiac when that was done) and, 2) I'm eating 95% gluten free already (for the past eight months).

However, if I'm going to get this test done, I'd like to make sure it's as accurate as possible.

Hi Jen. Here is an article that might answer some of your questions: http://www.celiaccentral.org/diagnosis/ Good luck!

Yes you do need to be eating gluten to get a positive test result. I have celiac & every so often the doc repeats the test to make sure gluten isn't sneaking into my diet, so far so good. I have no idea how long you have to eat gluten. I think if you have celiac it is obvious on a biopsy as the villi on the interior walls of the small intestine are shortened.

---edited from my previous reply after I reread your question--
There is some suggestion that eating zero gluten for a long time before a lab could produce a false negative. I don't think eating "95% gluten free" would produce that false negative though, because in someone with true celiac even tiny amounts of gluten set them off. The blood tests for it is also prone to other problems... the fact that you had an endoscopy with negative biopsy results is pretty much conclusive I would think.... IE even if they give you every lab test known to man they can't absolutely 100% definitively state that you do or don't have celiac without an endoscopy / biopsy.

Celiac itself is actually quite rare, the reason the term is bantied about far more than it used to be is the whole gluten free movement. The vast, vast, majority of people who chose to eat gluten free or say that gluten upsets their guts, don't actually have celiac--- many people even claim and believe they have celiac, but don't, because some naturopathic "doctor", (etc...) diagnosed it and they don't know any better...

I'm not eating gluten free because of the stomach thing - I wasn't even having stomach issues when I started doing that. I'm eating gluten free (or "wheat free" would actually be more accurate) because I have eosinophilic esophagitis and tested positive to wheat on allergy tests. It was an allergist (a medical doctor) who told me to avoid wheat and other foods I tested allergic to in order to stop eosinophils from attacking my esophagus. I didn't realize my GI doctor was ordering this test until after I'd left, because the form has a bunch of other blood tests on it as well. He didn't know I was largely avoiding wheat/gluten because my allergist's notes never got forwarded to him for some reason. The doctor who ordered this test is the same doctor who did the biopsy a year and a half ago - though at the time he was focusing on my throat, not my intestines. I don't know if celiac could develop in a year and a half (I wasn't having any stomach issues when the endoscopy was done), or whether a single biopsy could miss it, but obviously there's a reason he's ordering this test even though he's already done a biopsy.

There are plenty of good reasons not to eat wheat / gluten... I'm just saying that celiac is actually a pretty rare one. If you are working with a real allergist and GI they won't steer you wrong.

Yep, they are both real. :) Kinda bothers me that they don't seem to be communicating, though. And I know what you are saying about celiac - the same thing happens with people saying they are "allergic" to foods because they associate eating a certain food with feeling bad, even though they have never been tested by an allergist and probably aren't actually allergic. Drives those of us with real allergies (especially severe ones) crazy because it muddies the waters so much.

yeah the communication with the medical practitioners is absolutely terrible, which is largely because of privacy laws, which can be a very good thing too though. The only way to have a fighting chance at having any relevant history presented is to make sure the SAME primary care physician refers you to each and every specialist you ever see, every time.... and the PCP be CCd on all of the specialists dictations.... a big chunk of the PCPs job, to keep track of relevant history and include it in referrals to specialists, and refill prescriptions... Otherwise there is probably no link whatsoever between an allergist and the GI, unless one referred you to the other, which seems unlikely if they didn't send your history.

unfortunately it rarely works that way in my experience...

That's what's weird - the GI referred me to the allergist. The allergist sent the GI a letter after the initial visit, but he hasn't received anything since then (I've seen the allergist at least five other times). Next time I go I'll make sure my GI is listed as a physician to send information to.

I was wondering about this too. I had another negative test but I wasn't eating gluten for a few months before. I still don't eat wheat/gluten because I know I'm sensitive to it from my symptoms. I do cheat occasionally but pretty rarely now. If you go to the celiac.org site and read various things people have written about their celiac you will find that the diagnosis can actually be difficult especially if you don't have what I call severe celiac where tiny amounts will cause a huge reaction. You can still be getting damage slowly over time and never realize what is going on, sort of like with high bg.

Well I ate some wheat at dinner and my stomach is hurting really badly now. :( But that may just be because I haven't had it in so long. I read on a celaic site that you have to eat gluten for three months prior to the test. I don't think I'll do that long, but I might do at least a month (over the holidays wouldn't be bad!) or six weeks if I don't feel horrible.


This is a good site for information. You could also have gluten sensitivity which isn't true celiac, there is no way to test for that, but it can still cause damage over time so the best thing is just to avoid it as much as possible if not completely. That is the main treatment for celiac anyway if you're in the early stages unless you have true, severe reactions to gluten, then even cross contamination will cause a big reaction and you need total absence of gluten.

I think the problem is longterm damage to the digestive tract can still happen over time with sensitivity but the other risks of celiac such as lymphoma may not be there. I know the first time one of my docs recommended metamucil for my ibs I reacted so badly I had really terrible runs in about 5 minutes so I stopped that immediately.

Sorry about your stomach I also frequently get a stomach ache and feel ill after eating wheat, but not always so I'm not really sure what is going on. With ibs it is hard to tell because nearly anything can set you off, but I can say without wheat my symptoms are much better overall. I also use gluten free soy sauce etc. Wheat also spikes me like crazy 95% of the time.