Inova DGP

[ironictruth]

So I just found out some confusing news about my most recent positive blood work. Turns out it may not be positive. Inova has a Deamidated glidian test that is combined and they have one that separates the IGA and IGG.  The one that separates the test is often used by my local Labs without the word deamidated in it but looking it up online it is the DGP test.

 Because of recent discrepancies I've had these tests taken multiple times recently.

Both the combined test and the separated tests have a normal reference range of 1-20. 

 three times between late August and mid October I tested 28, 32 and 32 on the combined test.  I am on a gluten-free diet. I do not need any responses about eating gluten in order to get tested and all that kind of stuff because I have a lengthy history with this. We suspected a gluten thing because of the Big D and some other issues. And that's why the test was done.

 from July through November I also had the DGP test taken independently and IGA and IGG always came back under 20.  I have had a weak positive to the IGA 2 times in the past while eating gluten. Actually, one time was 4 weeks into a gluten-free diet after 6 weeks on a regular diet because the dr. Forgot to run the blood work.

 so I called  INOVA to ask them why it is that I could test positive on a combined assay but negative on a separated test. Because in one instance these tests were taken within 24 hours of each other. The combined test was positive and the separated test was negative and then the combined test was positive again within 24 hours.

 they had no real answer for me they told me it was possible just because I tested on the higher range of normal that's why the combined test came back positive. I asked them why the reference range was 1 - 20 for a normal test then. Because 21-30 is boderline and 31 and up is moderate/strong positive.  And they said that the labs could change  the reference ranges but generally don't. They then told me that the combined test was just a screening test and that it was not as sensitive as the separated test. But when I looked up their Selling material and the brochures they have the sensitivity rating up in the nineties for the combined test.

 I told her that was very confusing as I had inflammation in my small intestine recently but no blUnting of villi and a positive combined test three times. Now I'm not exactly sure what's going on anymore and will have to continue with more tests.  when I asked if she could point to any studies that discuss the difference in sensitivity and specificity between the separated Tests and the combined test she basically got pretty guarded and told me I should contact the hospital that Took my blood work.

 I searched for studies on this as well and cannot find a whole lot. I have also emailed a couple of celiac disease research centers to see if they might know the answer.

Anyone have any ideas?  I had thought originally that because the test is gliadin as an outpatient that they were using the old test and not the new DGP. That's why I had so many tests taken. But when I did the research I realized it was the DGP test.  As a result I got to open this box again about pain, nausea etc. 

[RMJ]

A good place to look for data on this type of test is the FDA website.  This type of test is approved by FDA via a "510(k)" process.  A manufacturer has to compare their test to an existing test.  Here is information where Inova compared the combined test to the separate tests (top of page 5).   This is not their most recent combined test, but that one just compared to this one, not to the individual tests.

Open Original Shared Link

They also compare their results vs expected results from celiac patients vs "healthy controls" (bottom of page 5).

If you want to see all the Inova tests just type their name into the "applicant" box on this page.  

Open Original Shared Link

This brings up pages of Inova tests that you can look through.  It is easy to pick out the celiac tests,  but I couldn't find a way to limit the search and get all of them.

[ironictruth]

This is very very cool. Thank you!