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Ttg Positive Predictive Value

rebz

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rebz Rookie
rebz
Posted

Hello

I have just come across a scientific paper written by my GI doc, looking at the positive predictive value of the tTG IgA test ie if you have a positive test what is the chance of you having celiac disease. The centre looked at 2000 patients with GI symptoms ,then how many of those with positive tTG results actually celiac disease. The answer is between 9-30%, depending if you are in a high or low risk group. The high or low risk group was defined by symtoms such as abdo pain, diarrhea etc..

I am really interested in anyones view of this - I have a positive tTG but negative EMA, and am scheduled for biopsy on Monday at this centre. Thought I had a high risk of having celiac disease because of the positive tTG, now I am totally confused..

Any ideas anyone ?

Rebecca

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nora-n Rookie
nora-n
Posted

I loked at several abstracta about this in www.pubmed.com the other day, adn noticed that they only recognized villous atrophy as celiac.

we know that the damage in the villi can be just in the tips, or show up as increased lymphocytes. Those woud be negative for celiac according to those standards.

Also, researchers have tested the biopsies for Ttg activity, and found out that villi that show noe signs af celiac , show Ttg antibodies in patients with suspected celiac......

You can be celiac and have antibodies in the gut and the villi are still there and look normal.....

Also, often the damage is patchy, so that 12-15 biopsies are recommended.

With me, they tok only 4. With daughter, they took 4 but only examined 2.....

BTW, have you read the latest blog entries at www.thefooddoc.com

nora

Jestgar Rising Star
Jestgar
Posted

I agree with Nora. Other studies have shown that the ttg levels may not rise until you have total, or near total villi destruction, so their interpretation is backwards. If you have destroyed villi you have a high probability of having high ttg levels, but having high ttg levels doesn't mean you will have sufficient destruction that they'll see it during a casual biopsy. It's a subtle distinction...

rebz Rookie
rebz
Posted
  • Author

Thank you for your knowledgable replies. You are correct that they look only for villous atrophy, not for lymphocytosis.

I think they usually do 4 biopsies at this centre, is it worth asking them to take more ?

From what you are saying even if the biopsy is negative, and hence they won't diagnose celiac, it would be worth seeing if I have dietary response.

Rebecca

ravenwoodglass Mentor
ravenwoodglass
Posted

Yes, even if the biopsy is negative, heck even if the blood test is negative a dietary trial gluten-free should be done. Not doing so can result in years of misdiagnosis and suffering and also permenent damage to the brain and other organs. As my GI said recently the tests we have for celiac are not extrememly accurate.

Tim-n-VA Contributor
Tim-n-VA
Posted

There is a lot of conflicting info. This is how I understand it for celiac:

1) Consume gluten

2) Body produces tTg

3) Damage occurs

The confusion frequently arises when the level of tTg or the amount of damage is not detected (or not considered significant by a medical person).

Is that correct?

Jestgar Rising Star
Jestgar
Posted

I think the order is:

1

3

2

Damage can begin before any other signs or symptoms are present. Some people only have signs of malabsorption, and only after a long time.

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hathor Contributor
hathor
Posted

One thing I've wondered about -- if you have malabsorption (at least according to Enterolab), does this mean villi damage or can it come about another way? I don't have the celiac genes. But I suppose if malabsorption means that the villi are damaged, I could call myself celiac. It would make explaining things to people easier :rolleyes:

confused Community Regular
confused
Posted
One thing I've wondered about -- if you have malabsorption (at least according to Enterolab), does this mean villi damage or can it come about another way? I don't have the celiac genes. But I suppose if malabsorption means that the villi are damaged, I could call myself celiac. It would make explaining things to people easier :rolleyes:

I have wondered that to.

paula

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