Positive Ttg Ab, Iga And Negative Ttg Ab, Igg

[Jbadeo]

Hello all. Just learning about celiac disease after a blood test came back positive. Can anyone help me interpret my results? Below I have included my index results and range:

TTG

tTG Ab, IgG Results: 0.89Index range < 0.90

tTG Ab, IgA Results: 1.53Index range <0.90

What is the likelihood I am positive for celiac disease with one result being positive (ttg IgA) and the other result negative (ttg IgG). Thank you in advanced for any insight,

JB

[mushroom]

The IgG is usually run as a backup in case you do not make normal amounts of IgA. See the following from celiac.com:

http://www.celiac.co...ests/Page1.html

How good are these tests?

If all of the blood test results are positive a celiac disease diagnosis is 90% accurate. However, there are several circumstances in which the tests can be inaccurate. IGA and IGG are two different varieties of antibodies which are produced by most peoples immune systems. There is a different blood test for each of the antibodies. Of the two tests, the IGA gliadin and IGA endomysial tests are the most accurate. However, this test can become negative relatively quickly after going on a gluten-free diet (3-6 months), which can cause a false negative test result. The IGG is less specific, and can sometimes be positive in non-celiacs. Also, about 4% of celiacs have no IgA at all! For these reasons it is very important that both tests are done for an accurate diagnosis. The biopsy is still considered the "standard candle" to confirm a blood diagnosis, and give a 100% sure diagnosis.

It is not necessary to test positive on every celiac test to have a confirmed diagnosis. There are several other tests such as the endomysial (EMA) which your doctor did not run.

[Jbadeo]

  On 10/27/2011 at 9:05 PM, mushroom said:

The IgG is usually run as a backup in case you do not make normal amounts of IgA. See the following from celiac.com:

http://www.celiac.co...ests/Page1.html

How good are these tests?

If all of the blood test results are positive a celiac disease diagnosis is 90% accurate. However, there are several circumstances in which the tests can be inaccurate. IGA and IGG are two different varieties of antibodies which are produced by most peoples immune systems. There is a different blood test for each of the antibodies. Of the two tests, the IGA gliadin and IGA endomysial tests are the most accurate. However, this test can become negative relatively quickly after going on a gluten-free diet (3-6 months), which can cause a false negative test result. The IGG is less specific, and can sometimes be positive in non-celiacs. Also, about 4% of celiacs have no IgA at all! For these reasons it is very important that both tests are done for an accurate diagnosis. The biopsy is still considered the "standard candle" to confirm a blood diagnosis, and give a 100% sure diagnosis.

It is not necessary to test positive on every celiac test to have a confirmed diagnosis. There are several other tests such as the endomysial (EMA) which your doctor did not run.

Thank you for the reply. So I am just trying to comprehend everything, and I am sorry if my understanding is unclear. Would my positive blood results not necessarily hold weight then, since my Dr did not run the complete panel? I have read about false negatives, but not much about false positives.

[Skylark]

  On 10/28/2011 at 3:38 PM, Jbadeo said:

Thank you for the reply. So I am just trying to comprehend everything, and I am sorry if my understanding is unclear. Would my positive blood results not necessarily hold weight then, since my Dr did not run the complete panel? I have read about false negatives, but not much about false positives.

No, no. Anti-TTG IgA is absolutely a positive result for autoimmunity and it is EXTREMELY likely you are celiac. It's typical to have positive IgA and not IgG if you have a normal immune system and are not IgA deficient. The handful of false positives with TTG IgA come about because TTG isn't 100% specific to celiac. It can also appear in other autoimmune diseases and inflammatory bowel diseases like Crohn's. TTG is considered a celiac screen and a positive result requires followup. The anti-EMA and/or anti-deamidated gliadin tests are specific to celiac and should be the next step before you go off gluten. Your doctor will probably also want to refer you to a GI for a biopsy.

There are also people who show TTG and other celiac antibodies, gluten sensitivity, but not villous damage. They're often told they are not celiac, but prospective studies show it's only a matter of time before the anti-TTG starts to do damage.