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Gliadin Iga


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#1 orangez28cam

 
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Posted 26 October 2010 - 09:51 AM

I recently had the celiac blood testing done. My Deamidated Anti Gliadin IGA was 55 (30+ is strong positive) and my TTG IGG was 6 (with 6-9 being weak positive). Every other test (and they did the full panel) was negative. I can't get in with a GI doctor unti Dec. 1st.

I've been researching my results online, and have found several sites that say the Gliadin tests are outdated and even "normal" people can have elevated levels? Anyone heard this? Do you think they are referring to the Deamidated Gliadin? I was under the impression that this was a very good test for celiac and replaced a test for gliadin that wasn't deamidated? Could I have a positive Gliadin IGA test and not have celiac? I have had lots of celiac symptoms for years and have been diagnosed with IBS, Raynaud's, Hypoglycemia, among other things. I was almost hoping for a Celiac Diagnosis because finally I might have the answer to feeling good for once! Is the IGA test really outdated and meaninless in a diagnosis?
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#2 ksymonds84

 
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Posted 26 October 2010 - 10:56 AM

I recently had the celiac blood testing done. My Deamidated Anti Gliadin IGA was 55 (30+ is strong positive) and my TTG IGG was 6 (with 6-9 being weak positive). Every other test (and they did the full panel) was negative. I can't get in with a GI doctor unti Dec. 1st.

I've been researching my results online, and have found several sites that say the Gliadin tests are outdated and even "normal" people can have elevated levels? Anyone heard this? Do you think they are referring to the Deamidated Gliadin? I was under the impression that this was a very good test for celiac and replaced a test for gliadin that wasn't deamidated? Could I have a positive Gliadin IGA test and not have celiac? I have had lots of celiac symptoms for years and have been diagnosed with IBS, Raynaud's, Hypoglycemia, among other things. I was almost hoping for a Celiac Diagnosis because finally I might have the answer to feeling good for once! Is the IGA test really outdated and meaninless in a diagnosis?


My understanding is that Anti Gliadin IGA is more specific to Celiac than Anti Gliadin IGG. IGG is more senstive however but can be present in other illness such as Chrohns. Here is some info from this site that I've copied for you. Bold is mine.

Anti-Gliadin Antibodies:

Both IgA and IgG anti-gliadin antibodies (AGA) are detected in sera of patients with gluten sensitive enteropathy (celiac disease). IgG anti-gliadin antibodies are more sensitive but are less specific markers for disease compared with IgA class antibodies. IgA anti-gliadin antibodies are less sensitive but are more specific. In clinical trials, the IgA antibodies have a specificity of 97% but the sensitivity is only 71%. That means that, if a patient is IgA positive, there is a 97% probability that they have celiac disease. Conversely, if the patient is IgA negative, there is only a 71% probability that the patient is truly negative for celiac disease. Therefore, a positive result is a strong indication that the patient has the disease but a negative result does not necessarily mean that they don not have it. False positive results are rather uncommon but false negative results can occur. On the other hand, the IgG anti-gliadin antibodies are 91% specific and have an 87% sensitivity. This means that they will show positive results more readily but there is not as strong a correlation with celiac disease. It is less specific. Patients with other conditions but not afflicted with celiac disease will occasionally show positive results. IgG anti-gliadin antibodies are detectable in approximately 21% of patients with other gastrointestinal disorders. This test might yield false positive results but is less likely to yield false negative results.
I'm sure others more knowledgeable than myself will come along with some answers for you too!
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Kathy

Gluten free 3/08
Negative blood work/positive endoscopy
Fructose Malabsorption
Soy free

#3 Gemini

 
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Posted 26 October 2010 - 11:06 AM

I recently had the celiac blood testing done. My Deamidated Anti Gliadin IGA was 55 (30+ is strong positive) and my TTG IGG was 6 (with 6-9 being weak positive). Every other test (and they did the full panel) was negative. I can't get in with a GI doctor unti Dec. 1st.

I've been researching my results online, and have found several sites that say the Gliadin tests are outdated and even "normal" people can have elevated levels? Anyone heard this? Do you think they are referring to the Deamidated Gliadin? I was under the impression that this was a very good test for celiac and replaced a test for gliadin that wasn't deamidated? Could I have a positive Gliadin IGA test and not have celiac? I have had lots of celiac symptoms for years and have been diagnosed with IBS, Raynaud's, Hypoglycemia, among other things. I was almost hoping for a Celiac Diagnosis because finally I might have the answer to feeling good for once! Is the IGA test really outdated and meaninless in a diagnosis?



The deamidated gliadin test is the newer version of the older, AGA/IgA and AGA/IgG tests. The older tests are still very useful to test for dietary compliance and were not used exclusively for diagnostic purposes. It was part of a panel of 5 tests used for diagnosis of Celiac Disease. The newer version is supposedly more accurate but I do not know much more than that about it. I am already diagnosed by 5 years so am not as familiar with newer diagnostic tests.

Having a positive on either of these versions means you are making antibodies to gluten. You may either be gluten sensitive or have full blown Celiac. Either way, you need to be following a gluten free diet. There have been recent studies which have shown that many, many people show some level of antibody activity to gluten, which sort of proves what I believe.......that there are many more folks with gluten problems than most doctors can even begin to fathom. I would suggest that your doctor do a complete Celiac panel and not just one or two tests. Then, if you need an official diagnosis to follow the diet, you could proceed to a biopsy but those tests are not 100% accurate either, for many reasons. Have you tried a dietary trial? That is usually the definitive proof of a problem, if symptoms improve.
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#4 Skylark

 
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Posted 26 October 2010 - 11:52 AM

So much confusion in these posts. You are very likely celiac orangez, and even if your biopsy is normal you may want to stop eating gluten. I imagine your GI will tell you this.

Kathy, the distinction is not between IgG and IgA, but between anti-gliadin and anti-deamidated gliadin peptide (DGP).

Gemini, anti-DGP is as accurate as anti-EMA and both more sensitive and specific than anti-TTG. There is no really reason to spend money and resources on more tests if that one is positive.

The celiac gut processes gliadin into deamidated gliadin with TTG. This only happens in conditions of intestinal injury where TTG is secreted to the lumen, not in a normal intestine. Deamidated gliadin is more immunoreactive than gliadin, and eventually leads to autoimmunity because the immune system gets confused and makes antibodies to TTG along with the deamidated gliadin. The TTG antibodies signal the immune system to attack the intestinal mucosa (or skin and nervous system in some people).

The old tests were for antibodies to plain gliadin, as the deamidation pricess has only been discovered in the past ten years. They were not very sensitive or specific and are considered outdated. They can be useful trying to diagnose gluten intolerance or gluten neuropathy. The newer test is deamidated gliadin peptide (DGP). The anti-DGP IgG has been demonstrated to be 98% specific for celiac, similar to anti-EMA and the anti-DGP IgA is almost as good. Since antibodies to deamidated gliadin are thought to trigger autoimmune antibodies, researchers think that people who have the anti-DGP and a negative biopsy are highly likely to develop celiac in the future. I don't think a proper prospective study has been done as with anti-EMA because the test is so new.
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#5 HardcoreDior

 
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Posted 26 October 2010 - 12:27 PM

Skylark, thank you for the detailed information, I am one who likes to research these kind of things to learn everything I can. However it definitely doesn't look like English to me.

Do you think you could define what DGP, EMA and TTG are, and why they matter? Can levels of these all be tested for, and if so, which is necessary and which are overkill? And would all tests require the person to eat Gluten in order to show a positive result?
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#6 Skylark

 
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Posted 26 October 2010 - 01:15 PM

It sounds like you need to read some introductory information on celiac testing. I was writing that for orangez, who has been doing more reading.

Try this University of Chicago information.
http://www.celiacdisease.net/testing

Another on testing from the NIH.
http://digestive.nid...sting/index.htm
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#7 Gemini

 
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Posted 26 October 2010 - 01:21 PM

So much confusion in these posts.



Gemini, anti-DGP is as accurate as anti-EMA and both more sensitive and specific than anti-TTG. There is no really reason to spend money and resources on more tests if that one is positive.

The celiac gut processes gliadin into deamidated gliadin with TTG. This only happens in conditions of intestinal injury where TTG is secreted to the lumen, not in a normal intestine. Deamidated gliadin is more immunoreactive than gliadin, and eventually leads to autoimmunity because the immune system gets confused and makes antibodies to TTG along with the deamidated gliadin. The TTG antibodies signal the immune system to attack the intestinal mucosa (or skin and nervous system in some people).

The old tests were for antibodies to plain gliadin, as the deamidation pricess has only been discovered in the past ten years. They were not very sensitive or specific and are considered outdated. They can be useful trying to diagnose gluten intolerance or gluten neuropathy. The newer test is deamidated gliadin peptide (DGP). The anti-DGP IgG has been demonstrated to be 98% specific for celiac, similar to anti-EMA and the anti-DGP IgA is almost as good. Since antibodies to deamidated gliadin are thought to trigger autoimmune antibodies, researchers think that people who have the anti-DGP and a negative biopsy are highly likely to develop celiac in the future. I don't think a proper prospective study has been done as with anti-EMA because the test is so new.


I am not sure why you are so confused over the previous posts.....I thought both were explained fairly well. As I stated, I am not an expert on the newer tests as I was diagnosed almost 6 years ago but the AGA IgA/IgG were never used singly as a diagnostic tool and are still extremely useful in testing for dietary compliance. The newer tests may be more sensitive but I know of no doctor or lab who would base this type of diagnosis on one test alone, unless the patient had flaming symptoms of classic Celiac Disease. Most people have insurance and doing a full panel is still considered the best way to go. If insurance coverage is a problem, and a patient doesn't need a definitive diagnosis to stick to the diet, then a dietary trial would be the next best thing to try. However, as so many people seem to doubt without a diagnosis, most will seek a formal one and a full panel gives a much clearer picture of what's going on.
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#8 Skylark

 
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Posted 26 October 2010 - 01:49 PM

How does a "full panel" of less accurate and specific tests give a clearer picture? It's hard enough to get positive bloodwork, let alone a positive on something that's 98% specific. There are actually articles in the medical literature encouraging doctors to diagnose celiac with positive DGP or EMA and avoid the discomfort of a biopsy unless symptoms do not resolve on a gluten-free diet. I don't know that the average clinician is that comfortable with DGP but it's a really good test. At this point, I would not be at all surprised if the GI moves straight to a biopsy.
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#9 orangez28cam

 
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Posted 27 October 2010 - 10:09 AM

Thank you all for your comments and feedback. Sounds like the tests I had were the correct most recent tests available. I was hoping that was the case. I've spent 27 years feeling sick and it would be absolutely wonderful to get a diagnosis and validate all of my symptoms. I feel like some kind of crazy hypochondriac always going to the doctor, requesting tests, complaining about my many symptoms and having them call it IBS. So frustrating! I just can't wait to meet with the GI doc and see what he has to say.
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