TESTING FOR CELIAC DISEASE

There is a well-established test protocol for celiac disease: A physician takes a set of blood tests during a period when the patient has not been on a gluten-free diet; then, depending on the results of the test, a physician might proceed with an upper endoscopy, long known as the gold standard for a celiac diagnosis.

The reason the blood tests must be taken when the patient has not been on a gluten-free diet is that the tests measure the patient's reaction (or lack of reaction) to gluten in the diet. (The longer a patient has been gluten-free, the less chance there is of measuring anything and getting useful results.)

Some physicians might want to take only one or two blood tests, but the Celiac Disease Center at Columbia University recommends the following set to maximize the chance of getting accurate results:

Anti-gliadin antibodies (AGA) both IgA and IgG
Anti-endomysial antibodies (EMA) - IgA
Anti-tissue transglutaminase antibodies (tTG) - IgA
Total IgA level

When it comes to the biopsy, care must be taken to ensure that at least 4 to 6 biopsy pieces be taken, that the orientation of the biopsies be done properly, and that, in the words of the Celiac Disease Center at Columbia University, "If the biopsy interpretation does not match either the clinical impression or serologic results the biopsy should be re-interpreted by a pathologist expert in the interpretation of gastrointestinal pathology." In other words, if the results of the testing seem to be inconclusive, an expert pathologist should review them.

Genetic tests are not a substitute for the above diagnostic process. At present, genetic tests can, at best, determine whether a patient is extremely unlikely to have celiac disease. They will not tell whether a patient has it.

In fact, no other diagnostic tests have yet been proven to be equal or superior to the blood test/biopsy protocol. One might, for instance, find references on the Internet to a stool test offered by Enterolab, but as of the time of this writing this test has neither been accepted by the medical community nor independently shown to be more reliable than the aforementioned protocol.

As recently as last June, Dr. Alessio Fasano of the University of Maryland Center for Celiac Research had the following exchange in the Clan Thompson Celiac Newsletter (Issue #83/June 21, 2006):

Dear Doctor, I was recently diagnosed with gluten sensitivity through a stool test. Simple, non-invasive, and cheap! While it doesn't tell me if I have intestinal damage, I really don't care because the treatment will be the same, regardless. I have reversed my bone density loss with a (nearly) gluten free diet, have no digestive complaints, and feel great. Why are stool tests for antibodies not used more frequently since they are so darn cheap? Is the mainstream medical establishment opposed to their use for some reason? Thanks, Jenny

Hi Jenny: The only reason why the stool tests are not as diffuse as the classic blood test is that they are not validated and, therefore, they are not recognized by the official organs that govern the laboratories [sic] activities. I am pretty sure that if other labs and other scientists will validate the stool test, it will be likely that this test will be used more wisely. Unfortunately, after many years, nobody has been able to reproduce the validity of this test. Sincerely, Alessio Fasano, M.D.

And just yesterday, Andrea Levario of the American Celiac Disease Alliance shared the following on the international celiac disease mailing list:

The tests being conducted at Enterolab are not "definitive" for celiac disease. In reviewing information on the Enterolab website, it states they are testing for "gluten sensitivity" and not celiac disease.

There are well accepted criteria for the detection and diagnosis of celiac disease. The tests used to fulfill these criteria have been subjected to scientific scrutiny and validation. To our knowledge tests of antibodies in stool or saliva have not been validated as a robust test for the diagnosis of celiac disease. Many insurance companies base their decision to cover the costs of testing on the scientific evidence that supports the testing of that individual (indication) and the actual test used (validation).

Our organization relies on the expertise of its physician members, as well as the recommendations of the:

- American College of Gastroenterology;

- North American Society for Pediatric Gastroenterology,

- Hepatology and Nutrition (NASPGHAN);

- NIH Consensus Panel on Celiac Disease; and

- Childrens Digestive Health and Nutrition Foundation

for the most current scientifically proven information on the diagnosis of celiac disease.

Alternate testing methods are being explored, but at present the diagnosis of celiac disease is best done by well-informed medical professionals using the blood test/biopsy protocol.