Celiac disease is more common, particularly among adults, and more easily overlooked than many clinicians appreciate, according to the American Gastroenterological Association (AGA) Institute’s Medical Position Statement on the condition.
The overall prevalence of celiac disease is estimated to be 1%—comparable to that of rheumatoid arthritis. What’s more, “most cases remain undiagnosed until later in life,” the Position Statement says. “Clinicians should have a heightened suspicion that celiac disease may be present at any age in both sexes and in a wide variety of clinical circumstances.”
This last phrase perhaps encapsulates the most essential lesson of the AGA’s statement and its accompanying Technical Review on the Diagnosis and Management of Celiac Disease. More often than not, celiac disease doesn’t look the way one might expect.
“The most crucial role for primary-care providers (PCPs) is detection,” says Joseph A. Murray, MD, professor of medicine at Mayo Clinic College of Medicine in Rochester, Minn., director of its celiac clinic, and an author of the AGA’s Technical Review. “While celiac disease in its classic form, severe malabsorption, [is seen by] gasteroenterologists, most patients won’t present with this but with a wide diversity of less well defined conditions.”
Testing for celiac disease
Serologic testing has improved markedly in recent years. Immunoglobulin (Ig) A tissue transglutaminase antibody (tTGA) and anti-endomysial antibody (EMA) tests are considerably more sensitive and specific than the older antigliadin antibody test. These assays are “largely responsible for the recognition that celiac disease is not a rare disease” and that it has a “broad spectrum of clinical presentations,” according to the Technical Review.
Patients who have unexplained chronic GI symptoms are the most obvious candidates for testing, and those with ostensible irritable bowel syndrome—particularly if symptoms are prominent after eating—should be considered for further evaluation as well, Dr. Murray advises. Lactose intolerance may be secondary to celiac disease: Suspect the latter in indi-viduals belonging to ethnic groups that are rarely affected by lactose intolerance. The possibility that diverse clinical presentations reflect “atypical” celiac disease should also be taken into account. (For symptoms and diseases associated with celiac disease, see Tables 1 and 2.) The authors note that:
- Endoscopic studies of patients with iron deficiency anemia (IDA) and without GI symptoms find celiac disease in
- 3%-9%. Screening should be considered in all patients with unexplained IDA.
- Prevalence is increased in patients who have osteoporosis
- and bone demineralization, particularly when these occur
- Testing should be considered for those who have Down syndrome, unexplained elevations of aminotransferases, autoimmune hepatitis, and primary biliary cirrhosis.
- The prevalence of celiac disease in patients with type 1 diabetes mellitus is 3%-8%: Celiac disease may play a role in persistent hypoglycemia and peripheral neuropathy in these patients.
- An estimated 5% of unexplained infertility is related to celiac disease.
The prevalence of celiac disease among first-degree relatives of those with the disorder is estimated at 10%; the threshold for testing should be lower for these individuals, although “there is little evidence to support screening” when they are asymptomatic, the Technical Review says. A similar approach is indicated for second-degree relatives, in whom prevalence is 2.6%-5.5%.
The need for biopsy
Intestinal biopsy is the next step in patients with positive serologic findings: Characteristic histologic changes in the distal duodenum are “the gold standard for establishing the diagnosis of celiac disease,” according to the authors of the Position Statement, and other findings (such as increased numbers of intra-epithelial lymphocytes) may be an indication of latent disease. It is important to perform both serology and biopsy before initiating gluten restriction, lest the picture be obscured.
Additional investigation, including IgA determination, HLA genotyping, and even biopsy, might be considered despite negative serology results when the clinical picture and/or family history warrant strong suspicion of celiac disease.
“Minimizing delay in diagnosis appears to have a variety of health benefits for patients with celiac disease,” the authors say. Besides the risk of osteoporosis, IDA, and other direct consequences of malabsorption, celiac disease is associated with excess mortality due to malignancy, particularly non-Hodgkin’s lymphoma (NHL). Mortality increases when diagnosis is delayed more than 10 years.