Ninety-six percent of people with celiac disease are undiagnosed. This is partly due to the fact that the symptoms can vary widely: diarrhea and constipation often affect children, while adults may have more subtle symptoms related to malabsorption, such as anemia or osteopenia (weakened bones). These varying symptoms can make getting a proper diagnosis more difficult.
According to the University of Chicago Celiac Disease Center, celiac disease is not the only disorder that can cause changes in the intestine. A celiac disease diagnosis, therefore, must be confirmed through other blood tests and the response to a gluten-free diet. Going off of gluten before having these tests can disguise the signs and symptoms of the disease. Depending on the length of time the intestine has been damaged, a gluten-free diet can most times heal the intestines completely.
One might wonder, “If I can go off the gluten and heal my intestines, why go through all of the testing?” The reasons are related to the varied symptoms and their causes. It may not be the gluten in the grains that is causing the problem, but perhaps a specific carbohydrate or other proteins than gluten. In addition, people who have a family member with celiac disease are at greater risk for developing the disease. If one doesn’t know for sure whether the disease is present, it can prevent family members from being tested.
There is also the “nocebo” effect. While a placebo is an inactive sugar pill that sometimes has the effect of making someone feel better; a nocebo is a harmless substance that is associated with harmful effects due to negative expectations. Think of trying to eat fish after having a bout of food poisoning that you relate to fish, even if it was actually caused by something else. If someone has eaten a gluten-containing food and feels ill, he or she may relate the illness to gluten, when it actually may be another component of the grain or the meal that caused the effect.
Nonceliac Gluten Sensitivity: Sense or Sensibility?
Ann Intern Med; February 21, 2012; 156:309-311