Biopsy Can't Rule Out Celiac?

[jajus100]

I have some questions for all of you. When I read the literature out there, it seems like most doctors say that the "diagnosis" for Celiac can only be given when the "gold standard" of biopsy test is done. This came out of some conference where the "expert" doctors were there.

When I read what many of you have written, it is that the biopsy can rule it "in" but not "out." The reason given is that they may not take the biopsy where the damage is actually taking place, or there might not be enough damage yet. Okay, that seems to make sense.

Now, when I read the results of the IGG and IGA gliadin tests, and see the specificity and sensitivity ratings, I would have to question them. The way the percentages were gotten, was by comparing the blood test to the biopsy gold standard. My question, is if a lot of the biopsies don't catch ALL of the cases of Celiac, isn't it possible that a lot of the positive blood tests that were shown to be "false positives" due to lack of biopsy proof, might actually be true positives? I'm still trying to figure out why the body would antibodies to gluten if all was well... Know what I mean? I'm also still waiting for my appointment with my GI which was scheduled a month out, but is finally taking place Tuesday.

[ravenwoodglass]

.  My question, is if a lot of the biopsies don't catch ALL of the cases of Celiac, isn't it possible that a lot of the positive blood tests that were shown to be "false positives" due to lack of biopsy proof, might actually be true positives?  I'm still trying to figure out why the body would antibodies to gluten if all was well...  No what I mean?  I'm also still waiting for my appointment with my GI which was scheduled a month out, but is finally taking place Tuesday.

<{POST_SNAPBACK}>

In answer to your question, yes. There are some like myself that are only found through dietary elimination and challange. In some countries the endo is considered the 'Old' Standard not the Gold. American Doctors are, for the most part, very, very far behind in the understanding of gluten intolerance. after my DD's endo the doctor even told her "well, your a LITTLE BIT celiac" thats like being a little bit pregnant! Your response to the gluten-free diet is the best diagnostic. My opinion of course.

[VydorScope]

I worte this a while ago to answer the bisopy ruling out celiac disease question...

This post may sound picky, but in the day and age we live in, everyone realy kind of needs to understand this. A bisopy for celiac disease can never be negative, and can never disprove celiac disease. Let me explain...

Do you have some dice? Pick up one, assuming its a fiar 6 sided die, role it couple of times. Your goal is to get as many  1 or 2's as you can. Roll it say 5 times.  I got 4,3,6,3,5 . In 5 rolls I did not score a single 1 or a 2. If I roll enough times I should evenutally get a 1 or a 2, but theres no mathmaticly way to define enough, with precison.  Took me THREE sets of 5 rolls to get my first 1 or 2, it was a one actully. So what does that have to do with celiac disease? Easy...

When they do a bisopy for celiac disease they take a random part of your small intestin and check it to see if there is evidence. Most docs will take 4 or 5 samples. If say 1/3rd of your instenice is damaged, then finding damage is the same as rolling a 1 or a 2 on a 6 sided die. The more rolls you make, the better your chances of getting a 1 or a 2, but you literly could roll a million times and never get a 1 or a 2, or you might roll 5 1's in a row. In my example, it would take THREE endoscopy's to diag celiac disease successfully.

You see, the english term "negative" in this use REALY means "not postive". That sounds picky, but its an important fact.

So what does that mean for any of us? Just this, the biopsy is only conclusive IF IT IS POSTIVE. Anything else is not conclusive, just merely non-postive.

NOTE: I am not a doctor, nor do I play one on the internet, but one of my degrees is in statisitics, so I do have a better then average understanding of testing methodogly, but claim no medical expertise of any kind.

<{POST_SNAPBACK}>

As for the blood test...(Im assuming its based on the bisopy as you state) its valid because of basic statistics. The "extreme" cases are lsot in the proccessing of the smapling data. Its normaly done on a 95% or there about confidence. Meaning 95% of all poeple with celiac disease will get a postive blood test.

When ever you deal with real indivual ppl you have error, thats just reality of it. Theres a lot of varition. If the diet works, and reverses symptons, then you have enough your answer, and many docs will consider that diagonstic.

[KaitiUSA]

There are certain blood tests that are very accurate for celiac. The complete panel needs to be done which consists of the following:

Anti-Gliadin (AGA) IgA (detects gluten sensitivity)

Anti-Gliadin (AGA) IgG (detects gluten sensitivity-least accurate of the tests)

Anti-Endomysial (EMA) IgA (detects damage)

Anti-Tissue Transglutaminase (tTG) (detects damage-most accurate of tests)

Total Serum IgA (rules out IgA deficiency...if you are IgA deficient the IgA results would not be accurate)

The biopsies can only rule celiac in. I am pretty much backing what Vydor said...it's a hit or miss chance. If there is sporadic damage or if it's in beginning stages than it has the chance of coming back negative even if you really do have it.

[jajus100]

There are certain blood tests that are very accurate for celiac. The complete panel needs to be done which consists of the following:

Anti-Gliadin (AGA) IgA (detects gluten sensitivity)

Anti-Gliadin (AGA) IgG (detects gluten sensitivity-least accurate of the tests)

Anti-Endomysial (EMA) IgA (detects damage)

Anti-Tissue Transglutaminase (tTG) (detects damage-most accurate of tests)

Total Serum IgA (rules out IgA deficiency...if you are IgA deficient the IgA results would not be accurate)

The biopsies can only rule celiac in. I am pretty much backing what Vydor said...it's a hit or miss chance. If there is sporadic damage or if it's in beginning stages than it has the chance of coming back negative even if you really do have it.

<{POST_SNAPBACK}>

I understand about the tests. That really isn't my question. It is about the percentages they give for accuracy of the tests. If biopsy isn't always positive with Celiac, then the accuracy of the tests on the percentage charts given in this site, may actually be low. In otherwords, some of the test examples, might have shown positive on the blood test, and negative on the biopsy, so they would be registered as a false positive, when maybe they weren't.

I also wonder why some people would be positive for IGG or IgA in the Anti-Gliadin tests, if they weren't Celiac. Why would the body be making those antibodies? Should people, regardless of whether it is Celiac or not, if they are IgG or IgA positive in the Anti-Gliadin tests be eating gluten?

[Wandering Hermit]

jajus100:

These are great questions. I was wondering the same thing myself. I'm trained as a physicist so I am always questioning the veracity of the stats I come across related to celiac disease.

This is the other one that bothers me: on the blood tests I want to know what the measurement error is. You cannot measure or quantify anything without the possibility of error, and this error can be estimated. In my initial bloodwork, I was high only for gliadin IgG, nothing else. Without even talking about specificity or sensitivity, I want to know what the +/- is on my score. If they tested me 100 times on the same day, what would be the spread in the measurements? How much does the particular technician influence the results? Or environmental factors? Etc.

I doubt I will ever see results of a study on the gauge capability of these things! It's too bad, because when someone gives me experimental numbers without some error, I know the numbers are significantly less meaningful. And for a biological system, where there are many, many confounding factors, it is even more of a crapshoot, in all likelihood.

It is because of the completely inconclusive results of my bloodwork and the fact that gluten-free diet has not done much to impact my symptoms that I am doing a (doctor prescribed) gluten challenge right now.

[Wandering Hermit]

And here is the other frustrating aspect of this. Kaiti gave a good list of the various blood tests. We know that each of these tests has an associated sensitivity and specificity. But what are these stats when the blood panel yields mixed results? If you are AG IgG positive and tTG negative, what is the sensivity/specificty for these COMBINED results???? You never see this addresed.

Moreover, depending on the doctor, some tests are far more meaningful. For example, here is a link to a Mayo clinic document on celiac disease:

Open Original Shared Link

They have an interesting diagnostic flowchart. Look at it.

According to this, if I am tTG negative, and not IgA deficient (both of which are true for me), not only do I not need to get an endoscopy, I would be immediately considered to NOT have celiac disease. End of story. It says nothing about what to do with me because I was AG IgG positive.

[VydorScope]

Oh I agree Hermint, I have a degree in statistics so I am coming from exactly the same mode of thinking, but I try not to bog ppl with out math degrees down with to many details.

[jajus100]

I had so many of the same questions. I wonder about the variance as well on the tests. Heck, I have even compared some of my older standard blood tests with new ones for the normal things, (blood count, liver panel, etc) and I was trying to compare three different tests to see what could cause the variability and wondered if it was just the nature of the test, or what had caused other changes. I did question the doctor about the measurement error, and she didn't know. I was high on the IgG, but had a score of 0 on the IgA and 1 on the Ttg, but no total serum IGA. On a scale of 1-10 being okay, I was a 21 for the IgG, but absolute 0 for the IgA.

I also had found that flow chart! I, too wondered about the positive IgG. I have found some sites that show a positive with Crohn's disease. In fact, some with Crohn's had the positive ttg test, but they were not Celiac--go figure. I also had some "rare fecal white blood cells," but tested negative for all parasites. That could mean inflamation, but from what? Celiac, colitis, or what...

The problem with the flow chart is that it is ONLY for Celiac. You would think we could find another flow chart that described our symptoms with OTHER possible outcomes.

I would also like to see what someone without Celiac scores on the five tests. What is a "normal" amount for each of the five tests. Do most people score 0, or do they score 5 or 6? Why does it become positive at a certain point. Is it just based on a percentile or something else. If ttg is very specific for Celiac, then what makes a 4 for example on my test being positive but a 1 negative. Does everyone have have some of this in their blood? If it shows damage, as I have read, why would people score anything on it.