False blood test positive?

[AndiOgris]

Hi all

I have had a very confusing year with celiac disease (or perhaps not as it turns out) and wondered if anyone can help me make sense of it?

My mother was diagnosed with celiac disease (in her 70s) a couple of years ago. I am in my early 40s and did not have any symptoms, but I took a blood test in November 2023 and it came back positive (TTG IGA 23.4 U/ml - normal range is below 7 U/ml). I was referred for a gastroscopy to confirm, which was scheduled for October 2024 (I use the UK health service, things move slowly!). The gastroscopy found no evidence of celiac disease. 

My gastroenterologist has asked me to retake the blood test, and it just came back negative (TTG IGA 1.6 U/ml - normal range is below 7 U/ml). Given the long wait between my initial positive blood test and my gastroscopy, I reduced my gluten intake but never avoided it fully. In the 6 weeks before the gastroscopy and the second blood test, I made sure to eat at least two slices of bread a day as recommended, and often I had significantly more. 

So what's going on? I understand that false positives are very rare for celiac blood tests, and usually associated with other serious diseases which I am fairly sure I don't have (my health is generally very good). After the negative biopsy, I thought that (i) either they did not take enough samples, or (ii) I have "potential celiac disease". But now that the second blood test has come back negative, I'm running out of plausible explanations... 

Can anyone make sense of this? I have not spoken to my gastroenterologist yet - I wanted to get a better sense of where I am beforehand so that I can ask the right questions. Under the UK system, specialist doctors can be very hard to get hold of, so I need to make the most of my time with him!

Thanks!  

 

   

[trents]

Welcome to the forum, @AndiOgris!

Recently upgraded guidelines for the "gluten challenge" recommend the daily consumption of at least 10g of gluten for at least 2 weeks to the day of testing to ensure valid testing, either for the antibody testing or the endoscopy/biopsy. 10g of gluten is roughly the amount found in 4-6 slices of wheat bread.

So, there is a question in my mind as to whether or not your gluten consumption was intense enough to ensure valid testing the second time around. And was the tTG-IGA the only antibody test that was run? That is far from a comprehensive celiac panel.

Concerning your negative biopsy, there is the possibility of patchy damage that was missed due to inadequate sampling as you alluded to. There is also the possibility that the onset of your celiac disease (if you have it) was so new that there had not yet been time to accumulate damage to the small bowel lining. Your total lack of symptoms at the time of diagnosis would seem to support this idea.

Having said all that, and this is my informal observation from reading many, many posts like yours over the years, I wonder if you are on the cusp of celiac disease, crossing back and forth across that line for the time being.

My suggestion would be to keep a close eye on this for the time being. Watch for the development of symptoms and request a more complete celiac panel a year from now. Here is an article that discusses the various antibody tests that can be run for celiac disease. Note: The EMA test is kind of outdated and expensive. It has been replaced by the tTG-IGA which measures the same thing and is less expensive to run.

 

[AndiOgris]

Hi Trents,

Thanks for your response! And yes, the TTG-IGA was the only test done. We did some more general blood tests at the time of the initial celiac test in 2023, but none showed any deficiencies usually associated with celiac disease. 

I'll mention the new gluten challenge guidelines to my doctor, perhaps he will ask me to do the test again? And I'll see what he says more generally...

Thanks again!

[Russ H]

Your initial test showed a moderately raised level of IgA tTG2. There are several causes of this apart from coeliac disease including: inflammation of the joints, bowel and liver. Transient rise in levels can be caused by an infection.

[trents]

Since your mother has celiac disease, I would still keep an eye on this as there is a genetic component. Study results vary wildly, but the numbers are that anywhere from 10% to almost 50% of the first degree relatives of those with active celiac disease will themselves develop celiac disease.

[knitty kitty]

I agree that you were not eating sufficient gluten prior to your endoscopy.