How can physicians diagnose gluten sensitivity when there's no accepted medical test for it? An expert group headed by Dr. Alessio Fasano, director of the University of Maryland Center for Celiac Research, proposes using an algorithm that first rules out celiac disease and wheat allergy, and then diagnoses gluten sensitivity based on the person's response to a gluten challenge.
The diagnostic algorithm, plus new classification language for all gluten-related disorders, was published Feb. 6 in the peer-reviewed online journal BMC Medicine (get the article here). It's intended to serve as a guide to improve the diagnosis and treatment of autoimmune gluten reactions (celiac disease, dermatitis herpetiformis and gluten ataxia), gluten sensitivity and wheat allergy.
The paper represents a joint effort to define gluten sensitivity and help diagnose it from 15 experts in the field, including Dr. Fasano, Dr. Peter Green, who heads the Celiac Disease Center at Columbia University, and Dr Marios Hadjivassiliou, a consultant neurologist and expert in gluten ataxia who practices at Royal Hallamshire Hospital in Sheffield, England.
In the paper, the 15 experts acknowledge that many people who have not been diagnosed with celiac disease are following the gluten-free diet: "It is now becoming clear that, besides celiac disease and wheat allergy, there are cases of gluten reactions in which neither allergic nor autoimmune mechanisms can be identified."
These cases can be classified as "gluten sensitivity," and their symptoms are indistinguishable from those in celiac disease, according to the paper.
But there are still plenty of physicians who don't believe gluten sensitivity exists, says Dr. Fasano. He told me in an interview that it's a bit of a "deja vu" moment -- he got the same reaction more than a decade ago when he first published research showing celiac disease was far more common than the one in 10,000 figure generally accepted in those days.
"I was laughed at," he says good-naturedly. "My job isn't to convince my colleagues. My job is to post the publication, and everyone will then disagree or agree with what I said."
He adds, "So far, I haven't seen any study that disputes the existence of gluten sensitivity. If that happens, we'll take a close look at it. Just saying 'It does not exist because I say so' is not a way to progress scientifically. The best scientists in my book are the ones which, number one, have open-mindedness, and two, have the ability to say 'I was wrong.'"
Dr. Fasano estimated that gluten sensitivity may affect 6% to 7% of the population -- far higher than celiac disease's estimated 1% or so -- in a paper published last year describing the potential molecular basis for the condition (see my posts on that research here and here).
In the paper published today, the panel of 15 experts proposes an algorithm that will help physicians diagnose gluten sensitivity by first ruling out celiac disease and wheat allergy (wheat allergy generally is pretty easy to distinguish from celiac and gluten sensitivity).
To determine whether a person has celiac disease or gluten sensitivity, the physician first would perform celiac disease blood tests. If those tests were positive, then they would proceed with an endoscopy to see if the person had the villous atrophy that's characteristic of celiac disease.
However, if the blood tests came back negative (as they do in so many cases), that wouldn't be the end of the story, as it is now. Instead, the research paper says, "then gluten sensitivity should be considered. A double-placebo gluten challenge will be the final step to either confirm or rule out gluten sensitivity."
To perform that double-placebo gluten challenge, the person who may be gluten-sensitive would eliminate gluten from her diet, and then "challenge" that by consuming a series of foods, some of which would contain gluten and some of which wouldn't.
Neither the person nor the physician would know which foods contained gluten. If the person reacted to those that contained gluten but not to those that didn't, then she could be diagnosed as gluten-sensitive. This type of challenge is considered the gold standard in food allergy testing.
(By the way, this procedure is not the same as the gluten challenge used to test for celiac disease in people who have been gluten-free for a while. There, your reaction to gluten doesn't count -- only your test results matter.)
Dr. Fasano says gluten sensitivity, as a condition, is at the same crossroads he encountered with celiac disease more than a decade ago, when most physicians believed it was an extremely rare condition. "At the beginning, I was like everyone else. I was skeptical, I sent [patients] home, I said 'No, it's all in your mind,'" he says. "But what I found was evidence of a different reaction to gluten that's not celiac disease."
University of Maryland scientists currently are researching potential biomarkers that could be used to create blood tests for gluten sensitivity, similar to the blood tests now used to diagnose celiac disease.