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Testing for Celiac Disease
We don't normally report on research that isn't directly related to food (that's what Dr. Gourmet is all about, after all). Today I'm going to make an exception because Celiac Disease is so challenging to diagnose. Stomach pain, diarrhea and bloating, some of the more common symptoms of Celiac, can also mean anything from gallbladder disease to Irritable Bowel Syndrome.
At this time the only way to definitively diagnose Celiac Disease is by doing a biopsy of the small intestine, which is where Celiac Disease does its damage to the body. That said, in this health care environment we doctors can't just send everyone with abdominal pain to have a small bowel biopsy - the current estimate is that less than 1% of the population has true Celiac Disease. Better to do other, less invasive tests first. Fortunately, there are several blood tests available, but they are not as definitive as a biopsy. They do yield some false positives and sometimes false negatives.
In this month's issue of JAMA, researchers published a review of the current literature on testing for Celiac Disease in those with gastrointestinal symptoms (2010;303(17):1738-1746). When a patient presented with diarrhea, for example, how likely was it that they had Celiac Disease? Compared to doing blood tests followed by a small bowel biopsy, were symptoms alone sufficient to justify having the biopsy done? Is doing a blood test really necessary?
The researchers identified 16 studies including over 6,000 people who had one or more gastrointestinal symptoms. In all the studies, when a patient was suspected to have Celiac Disease, that diagnosis was ultimately confirmed or disproved using small bowel biopsy. For some patients, blood tests were done before sending a patient for biopsy, while for other patients there were no blood tests prior to the biopsy.
Overall the researchers found that abdominal symptoms alone were not reliable indicators of Celiac Disease. Those with diarrhea, for example, who were sent to have a biopsy done without having a blood test first had very few positive diagnoses of Celiac Disease. Those with diarrhea who did have an initial positive blood test had a much higher likelihood of the diagnosis of Celiac Disease being confirmed through biopsy. Other abdominal symptoms, including chronic diarrhea, constipation, unexplained weight loss, nausea or vomiting, or just pain, had similar results: a small bowel biopsy done without doing a blood test first most often showed no evidence of the problems in the small bowel caused by Celiac Disease.
What this means for you
A biopsy of the lining of the small intestine remains the only definitive way to diagnose Celiac Disease. This review of diagnostic tests shows that the appropriate first step when your doctor suspects Celiac is to do a blood test, then follow up with a biopsy if it is indicated. Jumping directly to a small bowel biopsy when the patient has gastrointestinal issues really would be doing unnecessary procedures.