How Likely Are Lab Errors?

[Brit1612]

We have been anxiously waiting doing our sons bloodwork, post gluten challenge, since it will be the first time ALL the correct test are being ran, while being on gluten.

 

I am going to give you the original results (WHILE GLUTEN FREE) and then the results I saw yesterday..... (I can't help but wonder "are these even accurate?)

 

On Gluten-FREE diet:

 

ttg igg -- 15 (positive - reference range is <6 for negative)

dgp igg -- 3 (negative -reference range is < 20)

 

After 10 weeks of gluten challenge:

 

ttg igg -- < .8

dgp igg -- < .4

 

Serum IGA -- 9 (reference for his age should be > 30 I believe.

Serum IGM -- 45 (said "low" on the sheet but I don't know what the range should be for a 2 year old)

 

The IgA based test were negative both times, but considering the low IGA level I'm assuming that is irrelevant.

 

 

I have not heard from the GI about her interpretation of the results.  Am I wrong to think these results just seem weird!  I am happy they are negative, but I don't know if I should trust them or not.  Would his ttg igg level drop all the way down to less than one in a matter of 2 months (while eating gluten)?  

 

Do these results really indicate that he does NOT have celiac after all?????  

 

I have heard a lot about low IGA being more common in celiacs, but does anyone know what it could mean that both his IGA and IGM was low? (IGG and IGE were both in normal ranges)

 

One more question, he is on ammoxicilin for a sinus infection.  He had been on it about 3 days before the test, could this affect the results at all?  THanks again for all the support.

 

 

 

[cyclinglady]

I do not know! Sorry! My heart goes out to you. Diagnosing tiny children can be difficult. There are so many scenarios and his case is a bit strange. I did read in Dr. fansano's, "Guten Freedom" that "10 to 20 percent of celiac disease patients test negative to serology screening tests." With his serum IGA deficiency and both positive and negative blood tests, coming up with a definitive answer is definitely beyond most of us here on this forum.

Has he been tested for genetic markers? Though....some 2 or 3 celiac patients do not have these genes.

Ugh! It is hard to say.

Keep us posted on what your doctor advises.

Oh, I think steroids can impact test results but not antibiotics, but ask your doctor about how fighting an infection might affect antibody results.

[nvsmom]

I think false positives are fairly rare.  This report, on page 12, discusses how accurate the positives are for celiac disease (specificity)  and they are quite high, but I am not sure if that includes lab error.

Open Original Shared Link

 

I think it is more likely that his body's inflammation went down along with his overdone autoimmune response.  Labs can vary day to day and week to week.  If you continue to worry, then retest and if it is negative then continue to retest every 6 months for a year or so to make sure he is not hurting himself with gluten....But if he had symptoms, and had positive tests, then chances are it is celiac disease.  I am afraid that I have never seen someone have two positive tests and not have celiac disease.  

[Brit1612]

Thank y'all for replying.  I don't think the original results were wrong, considering he showed positive two different times for the ttg igg, but I have a hard time understanding how he would be positive while gluten free, and now be negative after a gluten challenge????  I guess I was wondering how likely it was that these most recent (negative results) were wrong?

 

As for the accuracy of the positive test, the link shared does not mention ttg igg, most of the articles I have ready only mention the ttg iga.  The doctors do not seem to think that the igg version of the test (which is the one he was positive for) is specific to celiac.

 

It is so confusing and frustrating.  Especially because he did have "classic celiac symptoms" but now (only after re-introducing gluten) he seems much better.....

 

We are scheduled for the colonoscopy and upper GI on Feb 6th.

 

Thanks again!

[nvsmom]

Oops. You're right.  

 

This is the link I often refer to when the tTG IgG is discussed. It shows the specificity is about the same as the tTG IGA (if a tiny tiny bit better) but the sensitivity is much lower - it can miss more celiacs than it catches...

Open Original Shared Link

 

Good luck on the 6th.  What will they be looking for there.  Are they worried it could be crohn's?  

[Brit1612]

Thanks for the link.....I will check it out in just a second.  Not sure if she is looking for something specific with the colonoscopy or is just doing it because he is already going to be under.   She said she didn't want to have to do the colonoscopy later down the line if we were still needing results.  She specifically told me that with his positive reducing substance, positive ttg, and low Iga that she believes it is celiac.  We just haven't been able to prove it, but I don't know if her opinion will change after these last blood results (still waiting to hear from her). 

 

I have wondered if we should be concerned about Chron's but his issues have seemed to point at celiac more.  Do they resemble each other outwardly?

[nvsmom]

The symptoms of crohn's can be similar to celiac disease but it is less common that celiac disease. Crohn's tends to affect the large intestine and the end of the small intestine - issues that can be seen in the colonoscopy.  With such a young guy, chances are it is not crohn's.  Your doctor probably just wants  to check everything.

[Brit1612]

That's what I figured.  I just keep doubting everything.  Keep asking myself "he seems normal now, should we even be doing another surgery....etc"  It's so hard when you are dealing with someone who can't even tell you how he's been feeling.  

 

Do any of you know anything about the low serum IGM?  Especially since he has low IGA as well.

 

Thanks