UK NHS Blood Test Waiting Times

[EmNaz93]

Hey, apologies if this has already been asked, I couldn't see any recent chats about this. Could anyone who has received a Coeliac screening blood test on the NHS please share how long it took you to receive results? I've been waiting 3 weeks and just trying to suss how much longer it may be. I know they do TTG and then only do the EMA if the first test is positive so I'm speculating that after this long this might indicate that the first test is positive and they've progressed to the second one?

Thank yoi

[trents]

Welcome to the forum, EmNaz93!

Are you sure it's not the other way around? I would think they wouldn't go to the expense of doing the EMA unless the tTG-IGA was negative in the face of definite celiac symptoms. Normally, what follows a positive tTG-IGA is an endoscopy with biopsy. In the UK, however, if the tTG-IGA is 10x normal or higher they will often dispense with the endoscop/biopsy. The EMA is another blood test.

[EmNaz93]

Hey trents thanks for the reply. I get confused about what's what. This is the information I have about the test from the hospital that's running out.

'Current guidelines advise that samples for coeliac disease investigation are initially screened for tTG antibodies. 

EMA will usually only be required when the tTG result is positive in new patients. Tests within the coeliac screen panel that are not required will be reported with a comment stating this.'

[trents]

Okay. Well it sounds like you interpreted the instructions correctly. Perhaps the NIH has recently changed their protocol. We have a couple of moderators on this forum in the UK who may want to comment on this. But historically, the NIH has ordered an endoscopy with biopsy when the tTG-IGA was positive.

But you refer to the "tTG". Which one? There is a tTG-IGA and there is a tTG-IGG. Here is a primer:

Can you post the exact wording of the report's test results?

[EmNaz93]

Hey trents. Done some more looking up and the hospital says the do an IgA-tTG in the first instance and would only do an IgG if the serum is flagged as having a low RU value (which I understand to mean if it looks like you have an IgA deficiency).

And they'll do the EMA afterwards in either case where the results are suggestive of Coeliac disease.

[trents]

Do you know what your IGA-tTG score was and do you have the reference range for negative vs. positive?

You say, "Hey trents. Done some more looking up and the hospital says the do an IgA-tTG in the first instance and would only do an IgG if the serum is flagged as having a low RU value (which I understand to mean if it looks like you have an IgA deficiency)." This makes sense. A low RU value (otherwise known as total serum IGA) can cause false negatives in the individual IGA celiac tests.

However, what does not make sense is having a positive IGA-tTG trigger an EMA test. The EMA is very specific for celiac disease but less sensitive than the IGA-tTG. So what kind of a conclusion is reached when the IGA-tTG is positive and the EMA is negative? And this is not uncommon. It's why the IGA-tTG is the first line test and the EMA is a second line test - that, and the cost of doing an EMA.

[EmNaz93]

Hey Trents, the below snippet is everything I have an is word for word. 

Current guidelines advise that samples for coeliac disease investigation are initially screened for tTG antibodies. EMA-IgA antibodies are very sensitive and specific for coeliac disease (94-100%), therefore positive tTG ab samples are then confirmed using EMA. EMA are also used in the diagnosis of dermatitis herpetiformis (DH).

IgA-tTG/EMA antibodies are the first line test for coeliac disease. However, in patients with total IgA deficiency who cannot produce IgA, IgG antibodies are tested instead. If IgA deficiency is found, IgG-tTG/EMA are assessed and reported.

tTG: Negative: < 7 U/mL 
 Equivocal: 7 – 10 U/mL 
 Positive: >10 U/mL 
EMA: Normal result = Negative

I'm sorry I've probably not explained it well as I'm not familiar with these tests and what they mean, but hopefully the above will be clearer.

[EmNaz93]

And also just to clarify I've not received any results at all back.

Which is why I'm querying how long other people's test results took on average. And also whether the 3 week wait so far could be an indication of abnormal/coeliac positive test results. 

[trents]

39 minutes ago, EmNaz93 said:

And also just to clarify I've not received any results at all back.

Which is why I'm querying how long other people's test results took on average. And also whether the 3 week wait so far could be an indication of abnormal/coeliac positive test results. 

Sorry, I misunderstood your first post to say that you had the tTG results back already and that they were positive. So, you are conjecturing that the tTG may be positive because the test results are taking this long to be reported, correct?

"EMA-IgA antibodies are very sensitive and specific for coeliac disease (94-100%), therefore positive tTG ab samples are then confirmed using EMA." This conflicts with what I have understood about the sensitivity of the EMA. But now that I reread toe article I linked to you above, I see that I was mistaken about the sensitivity of the EMA. It is the expense of it that keeps it from being the "go to" celiac test.

Nonetheless, something has changed about the NIH protocols. Historically, they have not done an EMA before a biopsy. I wonder if the costs of the endoscopy/biopsy have dictated that change. The problem of possible conflicting results between the IGA-tTG and the EMA still remains, however. A biopsy would bring clarification as celiac disease damages the villous lining of the small bowel.

Sorry, but I cannot comment on your questions about the normalcy of the turn around time for test results. I'm in the USA.

Keep us posted.

Edited August 5, 2023 by trents

[EmNaz93]

No worries I know my description was a little confusing.

That's it exactly yes. And just hoping if anyone with experience of wait times on the NHS might be able to shed light on their experience.

Afraid I'm not sure about the second point. It may be that the NHS have differing ways of doing things VS elsewhere?

Thanks again for your quick replies

[trents]

Well, maybe I wasn't wrong about the sensitivity of the EMA after all: https://factdr.com/diagnostics/blood-tests/ema-endomysial-antibodies/

"The EMA-IgA test is an important marker for celiac disease, portraying a 99% accuracy rate. This test is expensive and involves a high degree of technical precision. It is used as an accompanying test along with the routine tTG-IgA test to confirm the diagnosis of celiac disease. This test implies that anyone with a high titer of EMA is sure to be a victim of celiac disease. However, the EMA test scores are much lower in sensitivity than the tTG-IgA test."

and

https://celiac.org/about-celiac-disease/screening-and-diagnosis/screening/

"IgA Endomysial antibody (EMA): The EMA test has a specificity of almost 100%, making it the most specific test for celiac disease, although it is not as sensitive as the tTG-IgA test. About 5-10% of people with celiac disease do not have a positive EMA test. It is also very expensive in comparison to the tTG-IgA and requires the use of primate esophagus or human umbilical cord. It is usually reserved for difficult to diagnose patients."

But your thought about the test results turn around time being longer when an EMA is ordered has merit. As the article I link explains, it requires a high degree of technical precision. It also requires the use of harvested organ tissue but non human organs can be used for that.

Edited August 5, 2023 by trents

[Russ H]

4 hours ago, EmNaz93 said:

Hey Trents, the below snippet is everything I have an is word for word. 

Current guidelines advise that samples for coeliac disease investigation are initially screened for tTG antibodies. EMA-IgA antibodies are very sensitive and specific for coeliac disease (94-100%), therefore positive tTG ab samples are then confirmed using EMA. EMA are also used in the diagnosis of dermatitis herpetiformis (DH).

IgA-tTG/EMA antibodies are the first line test for coeliac disease. However, in patients with total IgA deficiency who cannot produce IgA, IgG antibodies are tested instead. If IgA deficiency is found, IgG-tTG/EMA are assessed and reported.

tTG: Negative: < 7 U/mL 
 Equivocal: 7 – 10 U/mL 
 Positive: >10 U/mL 
EMA: Normal result = Negative

I'm sorry I've probably not explained it well as I'm not familiar with these tests and what they mean, but hopefully the above will be clearer.

The typical lab turn around time is 3 - 5 days. However, they need to receive the sample and return the results to the GP. They should have them by now.

As to what the blood tests measure. Coeliac disease is an autoimmune disease triggered by the body's immune response to gluten. As part of the immune response, the body makes antibodies to an enzyme called tissue transglutaminase 2 (tTG2). This is why it is an autoimmune disease, because the immune system will attack sites rich in this enzyme (gut, liver etc.). In the vast majority of people, the disease goes into complete remission on a strict gluten-free diet. People with coeliac disease also make antibodies against gluten but this is not very specific as people without coeliac disease often have the same antibodies. The initial screening test is for IgA tTG2 antibodies, which is very sensitive and specific for coeliac disease. If this is negative, they may check to see whether you are IgA deficient, which means you don't make a certain class of antibodies. If you are, they will perform tests using a different class of antibodies, IgG. People who test positive for IgA tTG2 at least 10x the reference range almost certainly have coeliac disease and in the UK can be diagnosed on this basis alone under current guidelines. People who are moderately raised may have coeliac disease but may also have another condition that raises IgA tTG2 antibodies such as Crohn's disease, liver inflammation, or arthritis. In such case, further investigation is warranted. As to EMA, I don't know why they are still using it as it is old technology that just detects IgA tTG2 antibodies but with less sensitivity - it is just like doing IgA ttG2 but with a 10x cut-off.