SAN DIEGO – An intestinal biopsy is almost always necessary to confirm celiac disease and is a must before committing a patient to the only effective treatment – a lifelong gluten-free diet.
Sticking to such a restricted diet is difficult and expensive, Dr. Sheila Crowe said at the annual meeting of the American College of Physicians. "A lifelong gluten-free diet sounds simple, unless you’re the patient. ... Eating out is very difficult, especially for children and teens who face a lot of peer pressure. And eating gluten free at home is expensive. Studies in the United States, Canada, and the United Kingdom confirm that a lifelong diet of gluten-free foods costs about three times more than a normal diet," said Dr. Crowe, professor in the division of gastroenterology and hepatology at the University of Virginia, Charlottesville.
Photo credit: ©Elsevier Inc.
Photo credit: ©Elsevier Inc.Dermatitis herpetiformis is a skin condition associated with celiac disease. Image A shows grouped excoriated papules and vesicles on the extensor surfaces of the elbows. Subepidermal blistering and papillary microabscesses (hematoxylin and eosin stain) is shown in image B. Granular immunoglobulin A deposits in the papillary dermis are shown by direct immunofluorescence in image C.
Because treating celiac disease requires this lifelong commitment, a positive serologic test isn’t enough to rule it in, she said. Nor are any of the available immunologic tests, including the most widely used – tissue transglutaminase IgA (tTG IgA) – specific enough to replace intestinal biopsy as the sole method for reliably diagnosing celiac disease. "A positive tTG test is not enough to place a person on this lifelong treatment without confirmation from an intestinal biopsy," she said. "This is especially important for children, because of the higher likelihood of false positives in that group."
tTG IgA has a very high sensitivity and specificity, but it isn’t perfect, Dr. Crowe said. "If you have a patient with clinical symptoms and the tTG comes back negative, there is still a 10% chance that’s a false negative. Another scenario could be a patient who has an autoimmune disease or a relative with celiac, and is experiencing celiac symptoms. If the tTG came back negative on that person, I would still do an endoscopy."
The only possible exception might be a patient with celiac symptoms who already has biopsy-proven dermatitis herpetiformis, with the classic immunofluorescent deposits at the dermal-epidermal junction. "If you biopsy these patients, the intestine will show the changes associated with celiac disease every time," Dr. Crowe said.
Celiac disease is no longer considered a disorder of childhood. "The disease is there lifelong. It appears you cannot suppress the immune response," she said.
The intestine rapidly responds to a gluten-free diet, "But the tendency to have an immunologic response to gluten is always there," Dr. Crowe said.
Relapses are common. Patients are most likely to "fall off" the diet when symptoms begin to abate, she said. They may simply feel "cured" and resume old eating patterns, or they may drop the diet because of changes that can occur as the intestine heals. "If a patient had diarrhea and malabsorption of nutrients, they might find themselves getting constipated and gaining weight on the gluten-free diet, fall off, and get ill again. Even if the intestine is healed, the vast majority of data tell us that patient will relapse," at some point after abandoning the dietary restriction, Dr. Crowe said.
This can lead to the development of refractory celiac disease, in which the intestine fails to recover despite a gluten-free diet. Patients with refractory celiac disease may be unable to fully absorb nutrients and need supplemental feeding methods.
The goal of celiac management is to promote intestinal healing, optimize nutrition, and avoid long-term damage, Dr. Crowe said. "It’s key to bring in a knowledgeable dietitian to help. And I mean knowledgeable – not someone who is going to hand your patient a diet sheet and that’s all."
Many celiac patients are already nutritionally compromised at the time of diagnosis. "This is the time to measure their nutritional parameters," Dr. Crowe said. "They may need supplements. Many are deficient in vitamin D, iron, folate, zinc, or other trace elements."
The risks of untreated disease "are not inconsequential." Patients can develop problems related to nutrient malabsorption, including osteopenia, infertility, miscarriage, and intrauterine growth restriction, and are four times more likely than the general population to develop a malignancy.
Guidelines for managing nutritional status exist, but there are no evidence-based treatment guidelines for celiac disease, Dr. Crowe said. "Aside from nutrition, you have to just advise them to follow good health practices. I have several patients who still smoke, and yet they’re morose about their gluten-free diet. I say, ‘Why are you worried about that? You need to worry about quitting smoking!’ "