Positive gliadin (deamidated) IgG, normal everything else?

[phosphene]

I've been searching through this forum and online but haven't gotten a clear answer, so I thought I would post my results specifically. My understanding is that a high gliadin IgG isn't really enough for a diagnosis, but what does it mean? I'm pretty confused. I definitely do have stomach and inflammation issues, but is it celiac or a sensitivity? With my endoscopy and biopsies I haven't gotten these results and my doctor recommended to do another biopsy. But I'd like to know what you guys think and if you've seen this before. Thank you in advance <3

Here are my blood test results:

- tissue transglutaminase Ab, IgG: Normal <1.0

- tissue transglutaminase Ab, IgA Normal <1.0

- gliadin (deamidated) Ab (IgA). Normal. <1.0 

- gliadin (deamidated) Ab (IgG). High. 209.2 U/mL. within high range greater than null.

(Value Interpretation ----- -------------- <15.0 Antibody not detected > or = 15.0 Antibody detected)

- immunoglobulin A. Normal. 303 mg/dL. within normal range between 47 and 310.

[trents]

Welcome to the forum, phosphene!

DGP IGG is quite high! It is not borderline. It certainly can indicate celiac disease but the test is not as specific as the tTG-IGA for celiac disease.

One thing that can throw false negatives for the tTG-IGA is low total serum IGA but that test was not ordered.  It should have been. Another thing that can drive the tTG-IGA score downward is commencing a gluten free or lower gluten diet ahead of the blood draw.

[Scott Adams]

This article might be helpful. It breaks down each type of test, and what a positive results means in terms of the probability that you might have celiac disease:
 

Quote

The sensitivity of the DGP-IgG test is reported to range from 75% to 85%, which means it can correctly identify individuals with the condition in about 75% to 85% of cases. The specificity of the DGP-IgG test is reported to range from 75% to 95%, which means it can correctly identify individuals without the condition in about 75% to 95% of cases.

At this point your doctor should schedule an endoscopy to confirm celiac disease. If this test should end up negative I would still consider non-celiac gluten sensitivity.

Approximately 10x more people have non-celiac gluten sensitivity than have celiac disease, but there isn’t yet a test for NCGS. If your symptoms go away on a gluten-free diet it would likely signal NCGS.

 

 

[Russ H]

14 hours ago, phosphene said:

I've been searching through this forum and online but haven't gotten a clear answer, so I thought I would post my results specifically. My understanding is that a high gliadin IgG isn't really enough for a diagnosis, but what does it mean?

You have isolated DGP-IgG. This is common in people who do not have coeliac disease and so by itself is not usefully predictive.

https://onlinelibrary.wiley.com/doi/full/10.1111/jpc.16071

[Scott Adams]

The study referenced looks at 26 children, and many other larger studies have shown the overall accuracy I mentioned. The next step would likely be another biopsy, if that is what your doctor recommended. To do that you'd need to keep eating gluten daily until all testing is completed.

[knitty kitty]

This article refutes the article in the post left by @Russ H.

Can we ignore the utility of deamidated gliadin peptide in the diagnosis of celiac disease in children?

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6697416/

And another article about the value of the DGP IgG test...

Diagnostic accuracy of anti-DGP (IgG) for celiac disease

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10071923/

 

[Russ H]

These references do not refute the paper I posted.

The second reference, "Diagnostic accuracy of anti-DGP (IgG) for celiac disease", does not compare isolated anti-DGP with anti-tTG2. This is a common mistake - when both anti-DGP and anti-tTG2 are raised it indicates coeliac disease. However, isolated anti-DGP is not predictive of coeliac disease in adults.

The first reference is a letter to the journal. The authors do not state when the serum testing was performed - at diagnosis or on a gluten-free diet - and there is no control group, so cannot derive a positive predictive value. It is not uncommon to have raised anti-DGP in the general population: someone with coeliac disease without raised anti-tTG2 antibodies may indeed have raised anti-DGP antibodies but this is likely incidental and not caused by coeliac disease itself.

[frieze]

On 9/20/2023 at 1:33 AM, trents said:

Welcome to the forum, phosphene!

DGP IGG is quite high! It is not borderline. It certainly can indicate celiac disease but the test is not as specific as the tTG-IGA for celiac disease.

One thing that can throw false negatives for the tTG-IGA is low total serum IGA but that test was not ordered.  It should have been. Another thing that can drive the tTG-IGA score downward is commencing a gluten free or lower gluten diet ahead of the blood draw.

The last test listed is IGA

[trents]

1 hour ago, frieze said:

The last test listed is IGA

Yes, I see that now. Yours is not low.

[aattana]

Hi Phosphone, did you ever figure out what elevated your DGP?  I am in the same boat.