What Exactly Measures an IGA Deficiency?

[bmarsh28]

Hi all, quick question. What levels of total IGA deem an "IGA Deficiency?" I've had a hard time finding research on what it is (is it lower than the range used? is it just low on the scale within the range used?) This is assuming that the total IGA is tested in the comprehensive celiac panel. For example, I am a 99 on a range of 87-352. In my opinion that would be low, but is it only considered low or deficient if it's below the range? Thanks!

Edited June 4, 2018 by bmarsh28

[kareng]

14 minutes ago, bmarsh28 said:

Hi all, quick question. What levels of total IGA deem an "IGA Deficiency?" I've had a hard time finding research on what it is (is it lower than the range used? is it just low on the scale within the range used?) This is assuming that the total IGA is tested in the comprehensive celiac panel. For example, I am a 99 on a range of 87-352. In my opinion that would be low, but is it only considered low or deficient if it's below the range? Thanks!

for testing for Celiac, that is not a low number at all. My understanding is that the test & ranges were developed for another reason but found to have a use with Celiac testing.  

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[bmarsh28]

22 minutes ago, kareng said:

for testing for Celiac, that is not a low number at all. My understanding is that the test & ranges were developed for another reason but found to have a use with Celiac testing.  

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Thanks for the response! I suppose I am a bit confused by the answer. I have been confirmed as having early celiac, or at least some form of latent celiac (high TTG IGG, and biopsy Marsh I, with genetic indicators) and I was looking to find a reason why my IGG was so high, but not my IGA, and my primary care physician was claiming an IGA deficiency because of some of the marked symptoms I had experienced in the past related to IGA deficiency but then my GI doc was saying I wasn't IGA deficient, so I was just curious who was right and what the numbers really mean.

[cyclinglady]

From my research IgA deficiency is defined at a number close to zero.  Your result is fine for celiac disease testing which is mostly used as a control test for the IgA tests (DGP, TTG).  Who knows why you tested the way you did?   If you find out, please share.   I test positive to only the DGP IgA (even in follow-up testing) and I had a Marsh Stage IIIB and my IgA is the opposite — extremely high.    

[pupppy]

I'm confused as well-isn't your IGA on the low end of the range?

[kareng]

1 hour ago, pupppy said:

I'm confused as well-isn't your IGA on the low end of the range?

They wouldn’t be deficient if they are still in the normal range.  But this test and it’s range was not developed for Celiac disease.  So the ranges aren’t relevant to Celiac.  That’s why the deficient for Celiac testing is different then the range printed on the test result. 

[pupppy]

5 minutes ago, kareng said:

They wouldn’t be deficient if they are still in the normal range.  But this test and it’s range was not developed for Celiac disease.  So the ranges aren’t relevant to Celiac.  That’s why the deficient for Celiac testing is different then the range printed on the test result. 

Yes, I understand it has nothing to do with celiac-it measures how much iga your body makes to validate the test. I agree he is not iga deficient because it is in the normal range. What I am saying is, since it is in the low end of normal, it could throw off the results somewhat and give a negative ttg iga.

I meant this as an explanation to why his ttg igg was positive, and his biopsy was positive

[kareng]

2 minutes ago, pupppy said:

Yes, I understand it has nothing to do with celiac-it measures how much iga your body makes to validate the test. I agree he is not iga deficient because it is in the normal range. What I am saying is, since it is in the low end of normal, it could throw off the results somewhat and give a negative ttg iga.

I meant this as an explanation to why his ttg igg was positive, and his biopsy was positive

But , if you read the link, the numbers need to be much lower to effect Celiac testing. 

[pupppy]

5 minutes ago, kareng said:

But , if you read the link, the numbers need to be much lower to effect Celiac testing. 

Well that link is wrong, every testing algorithm I've read stated that if your iga is below the range they order igg tests, and if any result is positive or equivocal proceed to biopsy. There is selective iga deficiency which is <1 mg/dl, and partial iga deficiency which is above that but below age matched ranges. I don't know where they got 20 mg/dl from-it is an extremely random cutoff and they don't cite any sources. So I don't trust that. 

I have seen samples that are slightly below the range for total iga, and test negative for ttg iga.

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[kareng]

I am probably still going to go with the Celiac experts who interpret these blood tests over the laboratory.  

[pupppy]

1 hour ago, kareng said:

I am probably still going to go with the Celiac experts who interpret these blood tests over the laboratory.  

It's not just quest, it's also mayoclinic, the American College of Gastroenterology, ARUP labs, and most algorithms out there. Partial iga deficiency still counts as iga deficiency. As long as it's below the range, the standard is to order igg tests

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edit: I am not trying to say your source isn't experts. They could be right, but even so if the iga is low then igg tests should still be ordered just in case. Better to catch everybody than gamble on the results (potentially false negative)

[cyclinglady]

I would like to add that if my GI had followed the American GI Association guidelines or many other algorithms (like you linked and I also share those links), my diagnosis would not have been caught.  I am not IgA deficient, yet I have NEVER (I am tested annually) had a positive on the TTG or EMA.  I only test positive to the DGP IgA.  I am biopsy confirmed with symptoms resolution (e.g. anemia) and my last endoscopy/biopsies revealed healthy, healed villi.  

The original OP had a normal Immunoglobulin A (IgA) result (within range). It was enough to validate the IgA tests she was given and used to help diagnose celiac disease.  Does everyone get all available celiac testing? Some celiacs are seronegative.  Some test oddly on the blood tests (like me).  Some are IgA deficient.  In those cases, going directly to biopsy can help determine a diagnose.  Unfortunately, many people do not have the financial resources, have insurance constraints (like some insurance only allows the TTG for screening) or a celiac-savvy doctor. 

Not everything follows a standard.  We are all unique.  This adds to the complexity of receiving a celiac disease diagnosis.  I wish it was more clear cut!