<<Disclaimer: Verify this information before applying it to your situation.>>

At 01:25 PM 5/9/01 -0700, Valerie Wells wrote:

>The anti-endomysial antibody is 99% predictive.

This statement alone may be misleading. The following explanation is from
Tom Ryan, Technical Service Specialist, INOVA Diagnostics, Inc.:

"Both IgA and IgG anti-gliadin antibodies (AGA) are detected in sera of
patients with gluten sensitive enteropathy (celiac disease). IgG
anti-gliadin antibodies are more sensitive but are less specific markers
for disease compared with IgA class antibodies. IgA anti-gliadin antibodies
are less sensitive but are more specific. In clinical trials, the IgA
antibodies have a specificity of 97% but the sensitivity is only 71%. That
means that, if a patient is IgA positive, there is a 97% probability that
they have CD. Conversely, if the patient is IgA negative, there is only a
71% probability that the patient is truly negative for CD. Therefore, a
positive result is a strong indication that the patient has the disease but
a negative result doesn't necessarily mean that they don't have it. False
positive results are rather uncommon but false negative results can occur."

I would interpret this to mean that at its best, the blood test is
reasonable accurate IF it is positive, but false negatives are quite
common. So if the test is positive, it's trustworthy, but if it's negative
the biopsy may very well still be necessary.

Now consider that many labs are simply not competent to evaluate the blood
tests, and patients have often been eating gluten free for some period
before the test, which may invalidate the test completely. And many docs
out there don't know this or fail to advise patients of it. The figures
I've read are that from 20 to 50 percent of the blood tests return false
negatives, as many on this list have learned the hard way.

But the biopsy can be just as problematic so far as returning false
negatives. Many GI docs take only three or so samples when celiac
specialists have recommended they take from 12 to 20. There is a reason for
this. The damage is difficult to see during the endoscopy, and the doc may
well not take the sample from a damaged section of the small intestine.
Again many labs are not competent to evaluate these biopsies. It is not
uncommon for one lab to return a negative, when another will say it's
definitely positive from the same sample. I have yet to meet a doc who
knows anything much about celiac. And I've met two who didn't even know the
word. Not to say there are not some who know a lot about it if you're lucky
enough to find one.

>And  EnteroLab's stool tests are supposed to be even more accurate &
>sensitive. [ http://www.enterolab.com ] The intestinal biopsy will
>someday be a thing of the past for diagnosing celiac disease.

I do hope this test turns out to be very trustworthy. But I'd feel much
better about it if some other celiac docs agreed that this test was as good
as Doc Fine feels it is. I'm crossing my fingers. So far, I just know any
test I'd trust enough to risk my health on. When I can still eat just a
touch of wheat and clear a crowded room about three hours later, I'm gonna
keep eating gluten free no matter what some test tells me. -vance