How Accurate Are The Tests?

[NoGlutenCooties]

How accurate/reliable are the tests for Celiac?
 

When I first requested my blood test for Celiac Disease, my doctor warned me that it may come back negative even if I had Celiac because the blood tests are not particularly accurate when they come back negative.  A positive result, however, is much more accurate.
 

My tissue number was also only 13.  The particular lab that I used considers anything 11 or under as negative, so I was not significantly above a “negative” result.  However, my biopsy showed moderate to severe damage and pretty extensive inflammation (even though I had been gluten-free for 3 weeks prior to getting the biopsy).

I’ve also read on this forum of people who had a negative blood test with a positive biopsy, and vice-versa.

 

Sounds very unreliable to me.

 

I mentioned a couple of weeks ago that the tests are not particularly reliable and others agreed with me.  I mentioned it again in a different thread and got a couple of fairly rude responses claiming that new research shows the tests are very accurate.

 

Does anyone have any conclusive information on this?  Following is some of the recent research I’ve done:

 

The National Digestive Diseases Information Clearinghouse indicates that various labs use a different panel of tests and at least one may be less reliable due to the technical difficulties in conducting the test and cites subjectivity in reading the test results. (Open Original Shared Link)

 

The Center for Celiac Research states, “The current diagnostic tests for celiac disease are very accurate, particularly when tTG and anti-endomysial antibodies are elevated.”  (Open Original Shared Link)

I find this confusing… does this mean the tests aren’t accurate if the levels for these antibodies are not elevated?  Can you have Celiac without these antibodies being elevated?  How elevated do they have to be for the tests to be accurate?

 

A recent article in Science Daily claims that over half the Australian population has the genetic marker for Celiac, and references a study that is researching the possibility of combining a genetic test with a blood test to diagnose Celiac – saving the patient from an invasive biopsy.  But the article states that currently, a biopsy is recommended for anyone with a positive blood test – ostensibly to confirm the diagnosis.  This indicates to me that they do not consider the blood test to be reliable enough to stand alone.  (Open Original Shared Link)

 

This article from this forum is dated, having first been published in 2010, but it claims the blood tests were inaccurate at least 80 percent of the time (at that time):  https://www.celiac.com/articles/22310/1/Blood-Testing-for-Celiac-Disease-Isnt-Very-Accurate/Page1.html

Have the tests really gotten that much more accurate in the last 3 years?

 

There was another article on NaturalNews.com that was also referenced on trulyglutenfree.co.uk that indicates that the tests that are being used are “ancient” and the biopsy is unreliable:
(Open Original Shared Link)
(Open Original Shared Link)

 

Finally… this article from celiac.org.au (2013) states:

“Importantly, blood tests are prone to error and a diagnosis of coeliac disease SHOULD NOT be made on the basis of blood test alone.” (emphasis in the original)
(Open Original Shared Link)

 

 

So what do you all think?  Are there new tests that are more reliable that just aren't being widely used yet?  Does it just depend on how good the lab and/or doctor are?

 

 

[Gemini]

 

I mentioned a couple of weeks ago that the tests are not particularly reliable and others agreed with me.  I mentioned it again in a different thread and got a couple of fairly rude responses claiming that new research shows the tests are very accurate.

So.....it would seem that when people do not agree with your question, you find them fairly rude? 

 

Celiac blood tests are pretty damn accurate for advanced Celiac Disease.  However, not everyone will test positive in the presence of true Celiac for a number of reasons, such as low or deficient Iga, going gluten free prior to testing, or having an inexperienced doctor who does not know how to test or evaluate the tests.  If you have pretty severe damage in your gut but are low on Iga, then you may test negative, even in the presence of severe damage. If you have minor to no intestinal damage as of yet, then you'll most likely test negative on the biopsy but could still trip the blood work. Depends on what level of Iga you have as a base. How many times have we heard of people who test positive on blood work and then have a negative biopsy?  Doctors will not diagnose celiac unless they see flattened/blunted villi and that only happens later in the disease state.

 

I failed all tests by huge numbers but was at the point of total villous atrophy and I was absorbing nothing. My total Iga was also extremely high so I am one of those serio-positive types.  Celiac testing, both blood and biopsy, have their drawbacks and it's more the skill of the person doing the testing and reading of the tests that will help with a diagnosis.  I don't know why everyone gets so hung up on the blood work not being accurate when biopsy results can be more problematic as far as accuracy.  In this area, studies mean nothing. There are too many variables with current testing.  However, if you have had celiac disease for awhile and are in the later stages of the disease, the odds of diagnosis go way up and this is why it takes an average of 11 years for a diagnosis in the US....30 years for me.  Immune issues are tricky to test for and the blood tests we have right now are pretty good but not without their problems. This is true for all AI diseases.

[kareng]

I probably posted this before for you.  These are people who treat Celiac everyday and are up on all the legitimate research.

 

Open Original Shared Link

 

 

In blood tests, are false positives less common than false negatives?

"Even though blood tests are quite accurate, they are falsely positive 1-3% of the time (i.e., being positive without the person having celiac) and, although less commonly, falsely negative 1-2% of the time (i.e., being normal when a person actually has celiac)."

 

 

Some of the issues I have seen, on this forum, in getting an accurate blood test:

 

- doctor who doesn't know anything about Celiac and gives bad info or reads test incorrectly

- being gluten-free at the time of tests

- old, less accurate tests ordered

- incomplete tests ordered, for example - not ordering total serum IGA &  only ordering TTG IGA

- tests that are not Celiac tests ordered - for example - doctors who order iron & ferritin levels or a dubious allergy test and if they are good tell the patient the tests say "no Celiac" 

- doctors who do not biopsy properly

- tests from "internet" labs

- small children

 

 

 

Edited:  Not trying to be rude - just factual.  

[NoGlutenCooties]

Something else that just occurred to me... it's probably difficult to determine when a negative result has been a "false negative".  If the patient later gets a positive result, either from a retest of the blood test or through a biopsy how do they know if the original blood test was a false-negative or maybe the person actually did not have Celiac yet at that time.

Proving a negative is not easy... so maybe the "false negative" estimates are not that accurate??

 

Gemini - no, I don't find anyone who disagrees with me to be rude.  Far from it.  I would just like to get as much information about this out there as possible, because it seems to be a common question for newbies who get confused about the test results.  I agree with your assessment that there are just too many variables in the current testing procedures.

 

KarenG - your list of common testing problems is very helpful as far as giving people things to watch out for.  Thanks!

 

 

Off-topic comment on doctors:

I once had a doctor give me a prescription for a UTI (urinary tract infection) - I forget now which drug, it was a long, long time ago - and he told me to start taking large doses of Vitamin C.  Lucky for me I looked up the drug in the PDR book and found that you are not supposed to take this drug in combination with Vitamin C because it can cause kidney damage!  So I guess that just goes to show you... you have to do your own research and be your own advocate and know that a person who is a doctor is still just a person - and just as fallible as the rest of us.