Celiac disease, also known as gluten
sensitive enteropathy is very common but frequently missed. It is an
autoimmune disease of intestinal damage due to gluten in people who are
genetically predisposed. Classic Celiac disease is diagnosed by abnormal
blood tests and an abnormal appearing intestine on biopsy and symptoms
that resolve with a gluten free diet.
Several blood tests exist for Celiac disease. They have varying degrees
of accuracy. Some are more sensitive, meaning they will be positive in
milder forms of the disease but are not specific, meaning a positive test
may not indicate Celiac disease. Others are felt to be very specific,
meaning that when they are positive, it is almost certain you have the
disease.
The most specific tests are tests for Celiac disease endomysial
antibodies (EMA) and tissue transglutaminase antibody (tTG) tests. These
two tests are IgA based tests and can be negative if you are deficient in
the immunoglobin IgA, which occurs in 10-20% of people with Celiac. When
either EMA or tTG are positive Celiac disease is very likely and usually
the intestine biopsy is positive. Recent studies indicate that the tTG may
only be positive in 40% of true Celiacs when mild degrees of intestine
damage are present on biopsy. Seronegative Celiac, meaning the blood tests
are negative but the biopsy is positive, may occur in up to 20% of Celiacs.
Antibodies for gliadin (AGA), the toxic fraction of gluten are
considered very sensitive but not specific for Celiac disease. Newer
assays for AGA antibodies for gluten that has undergone a chemical change
called deamidation appear to be more specific for Celiac disease (Gliadin
II, Inova) than the older gliadin tests. They also may be as or more
accurate than EMA and tTG antibody tests but are not yet widely available.
The most distressing problem for people with lesser forms of gluten
intolerance who have blood tests and/or biopsies that are normal or
borderline yet respond to a gluten free diet is either not being taken
seriously or knowing for sure if they are sensitive to gluten. For these
individuals stool antibody testing for antigliadin and tTG have been
helpful. Such stool testing has been performed in research labs and
published in a few studies but are only recently available through the
commercial lab, Enterolab. Founded by a former Baylor research
gastroenterologist, Dr Ken Fine, the tests are available to people online
without a doctors order but are not generally covered by insurance. Dr.
Fine, who patented the test, has yet to publish the results of his
findings in a peer reviewed journal so his tests are not widely accepted.
However, his unpublished data and the clinical experience of some of us
who have used his test have indicated the tests are very sensitive for
signs of gluten sensitivity. He reports that they are 100% sensitive for
Celiac disease and highly sensitive for gluten sensitivity of lesser
degrees. In the presence of symptoms, that reverse on a gluten-free diet,
abnormal stool antibody levels can be found in most people before blood
tests or biopsies become abnormal.
Small intestine biopsies during upper gastrointestinal endoscopy are
considered the “gold standard” for the diagnosis of Celiac disease.
However, recent studies have demonstrated that some people with gluten
sensitivity, especially relatives of Celiacs with little or no symptoms,
have changes from gluten injury to the intestine that can not be seen with
normal microscope examination. They can only be seen with special stains
not routinely done or with a research electron microscope. The special
stains are known as immunohistochemistry stains. They stain specialized
white blood cells called lymphocytes in the intestinal lining tips or
villi. When these lymphocytes are increased it is known as intraepithelial
lymphocytosis or increased IELs and it is the earliest sign of gluten
induced injury or irritation. Electron microscopy also reveals very early
ultrastructural changes in some individuals when blood tests and standard
biopsy examination are normal. When people who have these changes are
offered the option of a gluten-free diet they usually responded favorably.
In contrast, those who continue to eat gluten often later developed
classic Celiac disease.
What these studies suggest is that a “normal small intestine biopsy”
may exclude Celiac disease as defined by strict criteria but it is not a
gold standard for detecting gluten sensitivity. This fact is appreciated
by many individuals who have respond to a gluten-free diet they start
based on their symptoms, family history, suggestive blood test or stool
antibody test(s).
Another source of confusion is in the genetics of Celiac and gluten
sensitivity. Testing for specific blood type patterns on white blood cells
known as HLA DQ2 and DQ8 is increasingly being employed to determine if a
person carries either of the two gene pattern present in 95-98% of Celiacs
and predisposing them to the development of Celiac disease. Some use the
absence of these two patterns as a way of excluding the possibility of
Celiac disease and the need for testing or gluten-free diet. However,
there are rare reports of documented Celiac disease in people who are DQ2
and DQ8 negative. Moreover, recent studies indicate other DQ patterns may
be associated with gluten sensitivity though unlikely to predispose to
classic Celiac disease.
Testing for all the DQ patterns is advocated by Dr. Fine, based on his
experience with stool antibody test results. He reports that other DQ
types are associated with elevated levels of gliadin and tTG in the stool
and symptoms that respond to a gluten-free diet. According to his
unpublished data, all the DQ types except DQ4 are associated with a risk
of intolerance to gluten. Therefore, testing for all the DQ types allows a
person to determine if they carry one of the two high risk gene types for
Celiac disease or any of the other "minor DQ" genes Fine has found
associated with gluten sensitivity.
Enterolab's stool testing for gliadin antibodies and tissue
transglutaminase antibodies, though not widely accepted, have gained favor
in the lay public’s opinion as an option for determining sensitivity to
gluten either despite negative blood tests and/or biopsies or in place of
the more invasive tests. Most doctors still recommend the accepted blood
tests and small bowel biopsy for confirmation of Celiac. Though the
reports in the lay community are overwhelmingly positive they have not
been subjected to peer review in the medical community pending Dr. Fine
publishing his data or other researchers reproducing his results.
However, doctors open to the broader problem of gluten sensitivity are
reporting these tests helpful in many patients suspected of gluten
intolerance. Especially when someone has symptoms consistent with gluten
sensitivity but has negative or inconclusive blood tests and/or biopsies
these tests may be very helpful though some are not certain how to
interpret the tests. The national Celiac organizations are uncertain about
how to comment on their application without published research though a
recent article in the British Medical Journal did show stool tests highly
specific for Celiac. Dr. Fine has publicly commented that his unpublished
data demonstrates those with abnormal stool tests indicating gluten
sensitivity overwhelmingly respond favorably to a gluten free diet with
improvement of symptoms and general quality of life.
Another problem is that there are not universally agreed upon
definitions for gluten sensitivity or intolerance. This becomes especially
difficult for those who do not meet strict criteria for Celiac disease yet
may have abnormal tests and/or symptoms that respond to a gluten-free
diet. Those individuals become confused when they try to find information
but do not have a formal diagnosis of Celiac disease. Consensus in the
medical community on definitions and more research in this area is greatly
needed.
The few doctors who appreciate the spectrum of gluten intolerance or
sensitivity are outnumbered by the medical majority that continue to
insist on strict criteria for diagnosis for Celiac disease before
recommending a gluten-free diet. Doctors either unfamiliar with the
limitations of the tests as documented by Celiac research or who insist on
the strict criteria for Celiac being the only indication for recommending
a gluten free diet unfortunately may confuse or frustrate gluten sensitive
individuals. Some of these people then seek answers on the internet or
from alternative practitioners. Many have their diagnosis missed,
challenged, dismissed, or are misinformed. As a result they fail to
benefit from the health benefits of a gluten-free diet because they are
advised that it is not required based on normal blood tests and/or normal
biopsies. In the meantime, Celiac disease and gluten sensitivity continue
to be undiagnosed or misdiagnosed. For more information visit
http://www.thefooddoc.com.
 ABOUT
THE AUTHOR
Dr. Scot Lewey is a physician who is specialty trained and board
certified in the field of gastroenterology (diseases of the
digestive system) who practices his specialty in Colorado. He is
the physician advisor to the local Celiac Sprue support group and
is a published author and researcher. He is developing a web based
educational program for people suffering from food intolerance and
Celiac disease
http://www.thefooddoc.com
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