5yo with abnormal IgA w/reflex to TT IgG Ab

[ellyelly]

Hi there,

My 5yo recently had a celiac blood screen done due to some mild symptoms and strong family history of diagnosed celiac (grandmother, 2 aunts). Results as follows:

deamidated gliadin iga antibody- <0.2 (ref <0.2-14.9u/ml)

deamidated gliadin igg antibody- 2.8 (ref <0.4-14.9u/ml)

Ttg antibodies iga- <0.5 (ref <0.5-14.9u/ml)

IgA w/reflex to TT IgG Ab - 154 (ref 10-140mg/dl)

The GI wasn’t able to shed any light on the abnormal finding on the last measure- would greatly appreciate any insights!!! We are yet to understand what the test is for and what this abnormal finding might indicate…

 

thanks in advance!

 

 

[trents]

35 minutes ago, ellyelly said:

Hi there,

My 5yo recently had a celiac blood screen done due to some mild symptoms and strong family history of diagnosed celiac (grandmother, 2 aunts). Results as follows:

deamidated gliadin iga antibody- <0.2 (ref <0.2-14.9u/ml)

deamidated gliadin igg antibody- 2.8 (ref <0.4-14.9u/ml)

Ttg antibodies iga- <0.5 (ref <0.5-14.9u/ml)

IgA w/reflex to TT IgG Ab - 154 (ref 10-140mg/dl)

The GI wasn’t able to shed any light on the abnormal finding on the last measure- would greatly appreciate any insights!!! We are yet to understand what the test is for and what this abnormal finding might indicate…

 

thanks in advance!

 

 

"A reflex test is a laboratory test performed (and charged for) subsequent to an initially ordered
and resulted test. Reflex testing occurs when an initial test result meets pre-determined criteria
(e.g., positive or outside normal parameters), and the primary test result is inconclusive without
the reflex or follow-up test. It is performed automatically without the intervention of the ordering
physician. Reflex testing may prevent the need for additional specimen procurement from the
patient.
The reflex test adds valuable diagnostic information and is consistent with best medical
practices. Certain confirmatory reflex tests are required by law; but generally each laboratory
establishes its own criteria for medically appropriate reflex tests. A laboratory must disclose to
the ordering physician its protocol for performing reflex testing and provide the physician with
the opportunity to decline the follow-up tests."

from: https://apps.trihealth.com › trihealthlab › Reflex Testing.pdf

Your daughter's  tTG-IgG test is borderline high. IgG tests are secondary tests that can detect celiac disease in patients who have negative IgA test values. The IgG testing is valuable when total IgA is low. Your daughter's total IgA is technically in the normal range but it is at the low end of it. From reading a lot of posts on this forum similar to yours, I am forming the opinion that it is not uncommon for young children who do have celiac disease to produce abnormal tests results. https://celiac.org/about-celiac-disease/screening-and-diagnosis/screening/

If you have any doubts I would treat your daughter as if she has celiac disease. If her mild symptoms improve she likely has celiac disease brewing or possible NCGS (Non Celiac Gluten Sensitivity).

[ellyelly]

8 minutes ago, trents said:

"A reflex test is a laboratory test performed (and charged for) subsequent to an initially ordered
and resulted test. Reflex testing occurs when an initial test result meets pre-determined criteria
(e.g., positive or outside normal parameters), and the primary test result is inconclusive without
the reflex or follow-up test. It is performed automatically without the intervention of the ordering
physician. Reflex testing may prevent the need for additional specimen procurement from the
patient.
The reflex test adds valuable diagnostic information and is consistent with best medical
practices. Certain confirmatory reflex tests are required by law; but generally each laboratory
establishes its own criteria for medically appropriate reflex tests. A laboratory must disclose to
the ordering physician its protocol for performing reflex testing and provide the physician with
the opportunity to decline the follow-up tests."

from: https://apps.trihealth.com › trihealthlab › Reflex Testing.pdf

Your daughter's  tTG-IgG test is borderline high. IgG tests are secondary tests that can detect celiac disease in patients who have negative IgA test values. The IgG testing is valuable when total IgA is low. Your daughter's total IgA is technically in the normal range but it is at the low end of it. From reading a lot of posts on this forum similar to yours, I am forming the opinion that it is not uncommon for young children who do have celiac disease to produce abnormal tests results. https://celiac.org/about-celiac-disease/screening-and-diagnosis/screening/

If you have any doubts I would treat your daughter as if she has celiac disease. If her mild symptoms improve she likely has celiac disease brewing or possible NCGS (Non Celiac Gluten Sensitivity).

I can’t thank you enough for taking the time to reply- I am so grateful for your thoughts! Silly question, but which of the tests measures total IgA? 

[trents]

42 minutes ago, ellyelly said:

I can’t thank you enough for taking the time to reply- I am so grateful for your thoughts! Silly question, but which of the tests measures total IgA? 

This one: IgA w/reflex to TT IgG Ab - 154 (ref 10-140mg/dl)

The tTG-IGA is considered to be the centerpiece of serum testing for celiac disease. Supposedly, it combines good sensitivity with excellent specificity. The sensitivity of the test has been called into question of late, however, so the doctor ordered the deamidated gliadin igg antibody  test, which is less specific IIRC, but highly sensitive. Because your daughter was symptomatic and because of family risk factor, there was good reason to suspect celiac disease if any of the tests were positive. So the total IGA was "reflexively" ordered in response to the positive deamidated gliadin igg antibody test (and symptoms, family risk factor) to see if low  total IGA was causing false negatives for the tTG_IGA. Low total IGA will drive down the tTG-IGA proportionately. Hope this makes sense.

[ellyelly]

Thanks so much- this is all invaluable. 
 

Just so I’m sure that I’m understanding, the TtG IgG Ab (which appears not to have been reported?!) must have been elevated, triggering the lab to reflex to the total IgA to ensure it wasn’t low, which would have impacted the normal TTG IgA finding. Given that the total IgA is above average, this suggests that my child isn’t IgA deficient, so therefore the TTG IgA result is likely accurate? 
 

The outstanding questions from the lab results would then be:

- why is total IgA raised?

- why is TtG IgG raised? (Assuming it is?!). Is the 2.8 deaminated gliaden antibody IgG considered raised?

 

Huge thanks again for working this through with me!!!

[trents]

I'm sorry. I stated incorrectly about the deamidated gliadin igg antibody. It is not high. It is within reference range.

It does appear that the lab added on a total IGA to make sure that a possible low total IGA count was not causing a false negative for the ttg-IGA. Apparently, because of the symptoms and the family history they had expected to find a positive deadimated gliadin igg. This triggered the total IGA test. However, the total IGA was actually slightly higher than normal instead of being lower than normal and this is what the GI doc could not explain. This is my take on it based on what I understand about "reflex."

I gather the GI doc was not concerned about the higher than normal IGA? If he/she is concerned about that then the logical next step would seem to be finding out why the total IGA is high since the ttg-IGA is not driving that. Maybe other IGA antibodies are high. So, to me it would seem wise to begin a gluten free diet for your daughter to see if her symptoms improve and maybe have antibody testing done again in a few months to see if the total IGA drops into normal range.

Edited January 25, 2022 by trents

[RMJ]

Total IgA was measured and was a little high.  IF it had been low, then the TT IgG antibody test would have been done (reflex).  It was high, so the TT IgG antibody test was not done.

So the only question is why the total IgA was a little high.  Lab normal ranges for total IgA tend to vary a bit, so that slight elevation of total IgA is probably not a cause for concern, but definitely ask the doctor about it to see what they say.

[RMJ]

If you go by Mayo clinic reference levels, your 5 year old is within the total IgA range. I found another site that had 1-5 year olds 20-152 mg/dL, so your 5 year old is just barely above that.

Pediatric antibody reference levels

[trents]

Thank you, RMJ. If I recall correctly, you are a medical lab professional or in biochemistry?

[RMJ]

1 hour ago, trents said:

Thank you, RMJ. If I recall correctly, you are a medical lab professional or in biochemistry?

PhD Pharmacologist