Majority of Americans with Celiac Disease Unaware of Diagnosis

Recent research shows that approximately 1.8 million Americans have celiac disease, but 1.4 million of them are unaware that they have the disorder. In addition, 1.6 million Americans observe a gluten-free diet despite not being diagnosed with the condition.

These results come from a Mayo Clinic-led analysis examining the prevalence of celiac disease published in the American Journal of Gastroenterology. While research has been conducted on the prevalence of the disease in the past, the Mayo Clinic study is the most definitive to date.

Celiac disease is an immune reaction in the small intestine caused by eating gluten, a protein found in rye, barley, and wheat. Over time, this immune reaction causes damage to the lining of the small intestine and can cause malabsorption. A gluten-free diet is used to manage the disease, though roughly 80% of those following such a diet have not been diagnosed with the condition.

To determine prevalence of the disease, the researchers combined positive blood tests confirming celiac disease with interviews from the National Health and Nutrition Examination Survey, a nationwide population sample survey from the Centers for Disease Control and Prevention that combines physical exams and interviews.

The study included 7,798 people aged 6 years or older. Celiac disease was found in 35 survey participants, 29 of whom were unaware of their diagnosis. Serum samples from all participants were tested for immunoglobulin A (IgA) tissue transglutaminase antibodies. If the findings were abnormal, samples were also tested for IgA endomysial antibodies. Information about a prior diagnosis of celiac disease and following of a gluten-free diet was obtained by interview.

Celiac disease was defined as a reported diagnosis by a doctor and being on a gluten-free diet or a double-positive serology.

Nearly all the individuals in the Mayo Clinic analysis that were found to have celiac disease were non-Hispanic Caucasians, although previous research in Mexico has shown that the disorder could be just as common there as it is in the US. The study found that the rate of celiac disease in the US is similar to that found in European countries.

"This [study] provides proof that this disease is common in the United States," co-author Joseph Murray, MD, a Mayo Clinic gastroenterologist, said in a release. "If you detect one person for every five or six (who have it), we aren't doing a very good job detecting celiac disease."