A complete celiac panel includes the following tests:
antigliadin IgA and IgG (indicates gluten sensitivity)
anti-tTG and/or anti-endomysial IgA and IgG
total serum IgA (rules out IgA deficiency)
anti-reticulin IgA
To save cost, this panel is often reduced to a single test... the anti-tTG IgA. Insist on more than this single screening test!
Total serum IgA should always be run to rule out a condition called IgA deficiency. Other IgA tests are not reliable measures in someone who does not make enough IgA.
Many "experts" consider the gliadin and reticulin antibody tests as optional and outdated. It is said that antigliadin antibodies are not specific to Celiac Disease, but they are often the first to show and are of increased significance for those who may have gluten sensitivity manifesting as neurological disease. Reticulin antibodies have fallen out of favor even longer ago, but I do know of one person diagnosed with biopsy proven Celiac Disease who had only an isolated positive anti-reticulin antibody.
Other sources with information about serological testing:
The University of Maryland Center for Celiac Research still includes the antigliadin IgA and IgG tests. If your doctor doesn't want to include them... here is your best source! Dr. Fasano, who heads this center, is world reknown for his work with celiac disease.
This article contains a great diagnostic flowchart (figure 5)
Gluten-Sensitive Enteropathy (Celiac Disease): More Common Than You Think by David A. Nelson, JR, MD, MS
Dr. Rudert is the only celiac specialist I am aware of who may still include anti-reticulin antibodies when testing for celiac disease.
Clan Thompson's Celiac Site - Dr. Rudert on serological testing
What do the antibody tests mean?
Having a positive anti-tTG or anti-endomysial result means there is a very high probability (90-95%) that villous atrophy will be found on biopsy. However, a negative anti-tTG result does not absolutely rule out celiac disease~ it just makes it less likely.
Because a positive anti-tTG is such a strong indicator of intestinal damage, the trend seems to be moving away from using the gliadin antibody testing at all.
Isolated gliadin antibodies are a weaker indicator that the intestinal damage needed for a Celiac Disease diagnosis will be found. However, gliadin antibodies can be very meaningful, particularly for those who present with neurologic disease. There are also many people who have gastrointestinal and other symptoms that improve on a gluten free diet, whose only hint of a problem with gluten were positive antigliadin antibodies. Insist they include the antigliadin IgA / IgG, especially if you have neurologic symptoms.
M Hadjivassiliou, R A Grünewald, G A B Davies-Jones
”But antigliadin antibodies lack
specificity”
IgG anti-gliadin antibodies have been
the best diagnostic marker in the neurological
population we have studied. IgG
anti-gliadin antibodies have a very high
sensitivity for CD but they are said to
lack specificity. In the context of a range
of mucosal abnormalities and the concept
of potential CD, they may be the
only available immunological marker for
the whole range of gluten sensitivity of
which CD is only a part. Further support
for our contention comes from our HLA
studies. Within the group of patients
with neurological disease and gluten
sensitivity (defined by the presence of
anti-gliadin antibodies) we have found a
similar HLA association to that seen in
patients with CD: 70% of patients have
the HLA DQ2 (30% in the general population),
9% have the HLA DQ8, and the
remainder have HLA DQ1. The finding of
an additional HLA marker (DQ1) seen in
the remaining 20% of our patients may
represent an important difference between
the genetic susceptibility of patients
with neurological presentation to
those with gastrointestinal presentation
within the range of gluten sensitivity.
”But antigliadin antibodies have
been superseded by
anti-endomysial and
transglutaminase antibodies”
The introduction of more CD specific
serological markers such as antiendomysium
and more recently transglutaminase
antibodies may have helped
in diagnosing CD but their sensitivity as
markers of other manifestations of gluten
sensitivity (where the bowel is not
affected) is low. This certainly reflects
our experience with patients with gluten
sensitivity who present with neurological
dysfunction. Endomysium and transglutaminase
antibodies are only positive
in the majority but not in all patients
who have an enteropathy. Patients with
an enteropathy represent only a third of
patients with neurological manifestations
and gluten sensitivity. Antigliadin
antibodies unlike endomysium and
transglutaminase antibodies are not autoantibodies.
They are antibodies against
the protein responsible for gluten sensitivity.
It is also possible to have seronegative celiac disease. Some studies say this may occur in as many as 20%. A negative result on all antibody tests does not completely rule out celiac disease. If someone is highly symptomatic they should pursue a biopsy even if all blood work is negative.
Seronegative celiac disease: increased prevalence with lesser degrees of villous atrophy.PMID: 15185855
Reliance on serum endomysial antibody testing underestimates the true prevalence of coeliac disease by one fifth. PMID: 10720117
Anti-endomysial antibody negative celiac disease: does additional serological testing help? PMID: 11270789
Do I need a biopsy?
For a "gold standard" diagnosis, yes..you need a biopsy. If a "gold standard" diagnosis is not important to you, nobody can force you to have a biopsy if you don't want one. Some people are happy to let their response to the diet speak for itself. Others want to have a solid diagnosis before committing to strict dietary changes for a lifetime. Most, but not all, doctors will recommend a biopsy to confirm the diagnosis.
One thing is for sure, if you think you will ever want to have a biopsy done...the time to do it is BEFORE you begin experimenting with a gluten free diet. You must be consuming gluten for the biopsy to be accurate.
A biopsy may be important to rule out other co-existing conditions which might be contributing to your symptoms. However, if symptoms do not improve with dietary changes, a biopsy could always be performed at a later date.
Some doctors who take a common sense approach will diagnosis celiac disease based upon positive blood work and/or symptoms which improve on a gluten free diet alone. A positive anti-tTG, for example, is a very strong indicator that damage will be found on biopsy. So strong, in fact, that some doctors are beginning to question the necessity of performing the invasive procedure.
Is intestinal biopsy always needed for diagnosis of celiac disease? PMID: 12818277
In Summary
Whether or not you need biopsy proof of celiac disease is a personal decision to be made by you and your doctor. There are many pro's and con's to be considered, and a case can be built in either direction.