Can Celiac Disease Be Diagnosed on a Gluten-Free Diet?
Many of you write to me wondering if there is a test capable of diagnosing Celiac disease (CD) after you have stopped eating gluten.
It’s a terrific question. So many of us struggle with health problems for years, hoping for a diagnosis of something so we can finally label what’s ailing us, treat it and get on with life!
In some cases, gluten is removed from the diet in hopes of relief from negative symptoms. Even when there is a positive outcome after doing so, some individuals later wish to know for certain if they do indeed have CD.
That makes perfect sense, because there are legitimate reasons you may want or need to know whether or not CD is indeed your health issue.
See my article, 4 Reasons You may want to Know if You have Celiac Disease, for more.
Current Recommendation on Celiac Testing: Keep Eating Gluten!
You often hear – from me and from others in the gluten-free community and medical field – that an individual must be eating a normal gluten-filled diet in order for testing for CD to be accurate.
This is because in an individual with CD, the immune system produces antibodies in response to gluten consumed. That’s because the gluten is recognized as a “foreign invader” in the intestine of those with CD.
Blood tests used to screen for CD measure antibody levels in the blood in response to gluten.
If gluten-containing foods are removed from the diet prior to testing, antibody levels change. This may cause a negative test result, even in an individual who actually has CD.
Therefore, for accurate diagnosis, the general recommendation by medical professionals is to continue eating as normal (gluten included), then report symptoms to your doctor and follow through with testing.
Because going gluten-free prior to a diagnosis of CD is becoming more and more common, let’s look to science for a complete answer.
Diagnosis of Celiac Disease is Complicated
While the endoscopy and biopsy procedure, where tissue samples are taken from the small intestine where the damage from CD occurs, is the current gold standard in CD testing, there truly is no one test that can confirm CD, especially once an individual goes on a gluten-free diet.
Eliminating gluten prior to testing for CD diagnosis interferes with the tests used.
This is particularly true when an individual has been on a strict gluten-free diet for a long time, for example a year or more.
Intestinal biopsies can show normal or near-normal tissue after one or more years, and as we repeatedly say, without that definitive testing showing the hallmark small intestine damage and abnormalities of CD, a true diagnosis cannot be rendered. In fact, the American Gastroenterological Association recommends at least four tissue samples from different areas of the small intestine to confirm diagnosis.
Isn’t a Gluten Elimination and Reintroduction Diet Enough?
Even if an individual suspects they have CD and eliminates gluten completely, feels better then reintroduces gluten and the negative symptoms return, this is not enough to confirm a diagnosis of CD.
What this shows is the foods removed led to the symptoms that returned after reintroduction.
That could mean the individual has CD; however, it could also mean another gluten-related health issues is causing those symptoms.
In fact, research indicates only 36% of patients who feel better after adopting a gluten-free diet really have CD.
What to Do if You’re Gluten-Free but Now Want to Be Tested for CD
Again, the only way to be sure of an accurate diagnosis for CD is to be on a gluten-filled diet prior to, and at the time of, testing.
That means, if you wish to be tested, you must return to a gluten-filled diet. This is sometimes referred to as a “gluten challenge”, meaning you are challenging your system with a particular food or substance, in this case, gluten.
How Much Gluten Should You Consume on a Gluten Challenge?
There are no established medical standards for a gluten challenge. While research is limited in this area, it is generally agreed upon that consuming more gluten over a period of time will yield the most accurate test results (which, again, is why it is best to be tested prior to ever going gluten-free if you suspect CD).
While some physicians suggest eating a relatively small amount of gluten every day (one or two slices of bread) for two weeks is enough for accurate testing, the most reputable studies indicate that is not enough for antibody levels and small intestine damage to occur.
Unfortunately, for those who must return to a gluten-filled diet for testing, research shows it is likely necessary for an individual to return to and sustain a gluten-filled diet for about two months for accurate testing. During that time, the equivalent of at least two slices of bread should be eaten.
And it should be noted, some medical professionals still don’t think that is enough time or enough gluten to lead to the immune response and small intestine damage screened for in the current CD tests.
Best advice? If you think you have CD, get tested first, then go forward from there. It may save a great deal of discomfort and anxiety in the long run.