I have some questions on testing that I'm hoping someone can answer for me...Can a person have a positive TTG blood test for no reason? If a person has a positive TTG, and 1st degree relatives that have celiac disease, but has a negative biopsy and no apparent physical symptoms, is it really safe for him to remain on a gluten diet? Are just the elevated TTG antibodies a concern, even if no damage can be found? If the person did a gluten free trial, and his TTG returned to normal levels, would this indicate that he did indeed have celiac disease and should continue to avoid gluten? Thanks for any insight you can provide!
Can A Person Have A Positive Ttg Blood Test For No Reason?
Posted 08 March 2013 - 05:11 PM
Doctors would call that "biological variation". I don't think the test will be positive for absolutely no reason however it is elevated in MANY different disorders and infections. Studies have shown transient elevation during an infectious illness and it is notorious for being false positive in those with other autoimmune diseases (20 percent false positive rate in type 1 diabetes). The problem with starting a gluten free diet off the result right away is that you won't know if it was just a variation or if it was in fact early Celiac when it goes down. At this point, it is a patient by patient basis and it is important to take into other factors to make a decision for that specific person.
What may appear as "no reason" may be something that slipped the patients mind, perhaps an infection from a month or two ago, it could be a viral illness that wasn't too noticeable to the patient etc... Thyroid peroxidase for example can actually see slight elevations during the common cold. The titre of the antibody is big too for determining the cause, if it is 10x the positive limit then it is doubtful for other issues to raise it.
The Chicago Celiac center says that family members of Celiac patients can have an elevated TTG for no reason, in that case keeping an eye on symptoms or any other clues leading to possible Celiac along with periodic blood tests (could be with your yearly physical) would be an ideal way to handle it.
Posted 14 March 2013 - 05:49 AM
Been 6 months gluten free, her TTG normal, now EMA negative, and vitamin D nearly tripled.
If a family member of someone has high TTG but normal biopsy I would be sure other things are tested to get better answers, but no, I would not chalk it up to something else given the celiac genetics.
Posted 14 March 2013 - 07:23 AM
Thanks for your replys. His EMA was negative, and his Iron level was fine, but I don't think they checked his Vitamin D. For now he's decided to go on a gluten free diet to see if his TTG go down to normal levels. He wants to avoid follow up endoscopies (GI said he would need to do them periodically to check for damage, probably every few years) and symptoms that his family members have, including any increased risk for other autoimmune disorders. If his TTG goes down we were thinking that would indicate celiac really was the problem, even without fining anything on the endoscopy. I haven't ever heard about an infection causing high TTGs as toworry mentions. If thats true I'd like to read some more information on that. I had understood that the high specificity of the TTG would make celiac very likely for him.I know that the specificity depends somewhat on the level too - his TTG was 51 with less than 20 being negative, which our GI said was a moderately high positive on the test. If his level goes down to normal while he is off gluten, and he then does a gluten trial and it rises again, would that indicate the problem was indeed celiac disease? I guess my question is, if it appears that his TTG levels do rise and fall in reaction to a gluten free diet, would it really be fine to stay on gluten even if they found nothing on the endoscopy? It seems to me just the high TTG is a risk, but maybe I'm not understanding what the TTG really represents.
Posted 14 March 2013 - 11:48 AM
TTG is not that specific for celiac - that is why they like to do the EMA if tTG comes up positive. Here is what Wiki says:
Antibodies to tissue transglutaminase (ATA or anti-tTG) are found in patients with several conditions, including coeliac disease, juvenile diabetes,inflammatory bowel disease, and various forms of arthritis.
Or, as stated above, they can elevated by other transitory conditions in the body.
If the tTG is responsive to gluten, i.e., positive when on gluten, negative when off, I would think that would be a pretty positive indicator for celiac as the culprit. As Mom-of-Two says, the biopsy is not infallible.
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Posted 14 March 2013 - 11:57 AM
Posted 14 March 2013 - 05:43 PM
Type 1 diabetes associated and tissue transglutaminase autoantibodies in patients without type 1 diabetes and coeliac disease with confirmed viral infections. http://www.ncbi.nlm....pubmed/22585721
Helicobacter pylori infection is associated to increased levels of tissue transglutaminase in gastric mucosa cells
Anti-transglutaminase antibodies in non-coeliac children suffering from infectious diseases http://www.ncbi.nlm....les/PMC2810390/
It is well known that autoantibodies can be elevated during infection (remember, that does not mean it always is). There are many other studies showing elevated autoantibodies "specific" for other diseases too if you do some google searches and look through NCBI.
The problem with the TTG is that it is still relatively new when thinking about how long it has been on the market to be evaluated during other illnesses and diseases. Just like any other product created, the TTG is manufactured by a private research laboratory and is sold to testing labs and doctors in the same way a salesman would sell a car. They will market it in it's best possible light to get the sales while obeying relevant laws and requirements. The issue is that over time many of these tests are found not to be as accurate as they were once marketed.
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