A
group of researchers at the departments of
Gastroenterology, and Immunology at the Northern
Deanery of Newcastle upon Tyne, and Freeman Hospital in
Newcastle upon Tyne in the UK recently studied cases of
positive tissue transglutaminaseantibodies with negative endomysial
antibodies to determine whether or not such cases amount to
celiac disease.
By
way of background, the most sensitive and specific blood tests
for diagnosing celiac disease are those that detect immunoglobulin A (IgA) antibodies
against human tissue transglutaminase (tTGA) enzyme, and those that measure aspects of
connective tissue covering individual smooth muscle fibers,
endomysial antibodies (EMA).
Because
of the high sensitivity (up to 98%) and high specificity
(around 96%) reported for the tTGA assay, detection of tTGA is
currently the primary blood test used in screening for celiac
disease. The tTGA test also has a high negative predictive
value approaching 100%, which makes it an excellent test for
excluding celiac disease in both high and low risk groups.
EMA, on the other hand, has extremely high specificity values
close to 100% and positive predictive value values approaching
80%. However, compared with tTGA, EMA has lower sensitivity,
usually under 90%.
This
being the case, the present standard celiac disease screening
strategy is to first use tTGA, and then confirm positive
results using EMA. However, doing it this way, doctors often
end up with a group of patients who show divergent test
results.
For
their study, the researchers wanted to gauge the percentage of
patients with positive tTGA and negative EMA, but who were
confirmed with celiac disease upon biopsy, and to identify factors in these
patients that may help to increase diagnostic accuracy in such
patients. The research team identified 125 consecutive
patients with positive tTGA and negative EMA, who subsequently
underwent endoscopy with
at least two biopsies from
the second part of the duodenum.
The team
charted any tTGA result over 15 U/ml as positive. They
excluded any patients with known celiac disease at the time of
testing.
They then
reviewed patient notes to assess indications for celiac
disease serological screening, including the
presence of iron deficiency anaemia, and symptoms such as
diarrhea or weight loss, and family history of celiac disease.
They defined diarrhea as a bowel frequency of
more than three times a day.
They
then assessed histological evidence of celiac
disease based on subsequent duodenal biopsies, plus Marsh
grading. They categorized twelve patients (9.6%) as celiac
disease positive. Of these, 10 patients had positive
histology, and two patients had unclear histology plus an
overall clinical impression of having celiac
disease.
Source:
Family Practice News.com and celiac.com
Being
Gluten-Free 'Is Determined By Evolution', Says
Gastroenterologist
According
to Professor David Sanders, Consultant Gastroenterologist at
the Royal Hallamshire Hospital and University of Sheffield,
England, "Only for the past ten thousand years have we had
wheat-based foods in our diets, which in evolutionary terms
makes wheat almost a novel food. If you put that in context to
the 2.5 millions years that mankind has been on earth, it
makes sense that our bodies are still adapting to this food,
and more specifically, the gluten that it contains."
Sanders' comments were prompted following the recent claim that potentially up to 6% of the population could be suffering from gluten sensitivity, making it by far the most common gluten-related disorder after celiac disease. Celiac disease currently affects around 1% of the population, which is an 80-fold increase in reported cases since the 1950s, when only 1 in 8000 were susceptible, compared with 1 in 100, today.
Sanders' comments were prompted following the recent claim that potentially up to 6% of the population could be suffering from gluten sensitivity, making it by far the most common gluten-related disorder after celiac disease. Celiac disease currently affects around 1% of the population, which is an 80-fold increase in reported cases since the 1950s, when only 1 in 8000 were susceptible, compared with 1 in 100, today.
A recent
survey commissioned by the Dr Schär Institute identified that
GPs and dietitians frequently see patients with what they
believe to be gluten sensitivity but they are uncertain how to
manage the condition.
Its
gastrointestinal symptoms are general and include abdominal
pain and bloating, diarrhea, constipation and generic malaise.
Headache, fatigue, limb numbness and anemia make for
diagnostic difficulties too. The survey found that 90% of
dietitians and 86% of GPs claim to be aware of gluten
sensitivity but more than half have a limited or average
understanding of it.
Speaking
on behalf of the Dr Schär Institute, dietitian Melissa Wilson,
said, "The comments from Professor Sanders and the survey
results demonstrate that serious confusion exists when experts
try to diagnose or manage gluten sensitivity. GPs and
dietitians are telling us that they do not feel there is
enough information available, despite reporting a large number
of patients displaying symptoms associated with the
condition."
Source:
Science20.com
Gastroenteritis
May Trigger Celiac Disease
Food-borne infectious gastroenteritis could be triggering
some cases of celiac disease,
which might partly explain the rising incidence of the
autoimmune condition, a new paper suggests.
The
authors of the report - military researchers along with celiac
disease expert Dr. Joseph Murray from the Mayo Clinic -
focused on active duty personnel in the U.S. armed forces
between 1999 and 2008.
Altogether
there were more than 13.7 million person-years of follow-up,
they reported in The American Journal of
Gastroenterology.
The
incidence of celiac disease diagnoses increased five-fold from
1.3 per 100,000 in 1999 to 6.5 per 100,000 in 2008. The
research team identified a total of 455 cases of incident
celiac disease and compared those to 1 820 matched
controls.
Overall,
172 subjects had infectious gastroenteritis (IGE) within 24
months before their diagnosis, with the majority (60.5%) of
viral etiology. Multivariate analysis showed a significant
association between celiac disease and any prior IGE (odds
ratio, 2.06), which was stronger when the IGE was non-viral
(odds ratio, 3.27) vs viral (odds ratio, 1.44).
Given the
apparent association, the researchers suggest that infections
may "act as triggers for developing gluten intolerance through
molecular mimicry or other immune modulation
mechanisms."
Source:
(Reuters Health, David Douglas, July 2012)
-Beth Hillson Weekly Newsletter, July 17, 2012
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