Celiac disease

As many as one in every 100 to 200 persons in the United States has celiac disease, a condition resulting from an inappropriate immune response to the dietary protein gluten. The manifestations of celiac disease range from no symptoms to overt malabsorption with involvement of multiple organ systems and an increased risk of some malignancies. When celiac disease is suspected, initial testing for serum immunoglobulin A (IgA) tissue transglutaminase (tTG) antibodies is useful because it offers adequate sensitivity and specificity at a reasonable cost. A positive IgA tTG result should prompt small bowel biopsy with at least four tissue samples to confirm the diagnosis. However, 3 percent of patients with celiac disease have IgA deficiency. Therefore, if the serum IgA tTG result is negative but clinical suspicion for the disease is high, a serum total IgA level may be considered. Screening of asymptomatic patients is not recommended. The basis of treatment for celiac disease is adherence to a gluten-free diet, which may eliminate symptoms within a few months. Patients should also be evaluated for osteoporosis, thyroid dysfunction, and deficiencies in folic acid, vitamin B12, fat-soluble vitamins, and iron, and treated appropriately. Serum IgA tTG levels typically decrease as patients maintain a gluten-free diet. (Am Fam Physician 2007;76:1795-1802, 1809-10. Copyright [C] 2007 American Academy of Family Physicians.)

Celiac disease (or celiac sprue) is an autoimmune disorder with a prevalence of approximately 0.5 to 1 percent in the united states. (1, 2) it is associated with inflammation of the mucosa of the small intestine, which may result in villous atrophy. Celiac disease produces a variety of gastrointestinal symptoms that can begin at almost any age. Treatment consists of removal of gluten proteins from the diet, which improves and often eliminates the small intestine pathology.

Pathophysiology and Epidemiology

gluten proteins occur throughout our food supply and are relatively resistant to digestive enzymes. Incomplete digestion in the upper gastrointestinal tract results in peptide derivatives that are highly immunogenic to patients with celiac disease. In affected patients, after absorption in the small intestine these proteins interact with the antigen-presenting cells in the lamina propria causing an inflammatory reaction that targets the mucosa of the small intestine. Rye, wheat, and barley, alone or as ingredients in many processed foods, contain gluten and may elicit this immune response.

Two factors are involved in the development of celiac disease--consumption of gluten proteins and genetic predisposition. it is not completely understood how gluten sensitivity begins or whether early exposure to gluten proteins increases the risk of sensitivity. however, almost all patients with celiac disease express human leukocyte antigen (hla)-DQ2 or hla-DQ8, which facilitate the immune response against gluten proteins. (2) Concordance rates of 70 to 75 percent among monozygotic twins and 5 to 22 percent among first-degree relatives have been reported. (1,2,3) Patients with type 1 diabetes mellitus, Down syndrome, turner's syndrome, or an associated autoimmune disorder are at increased risk of celiac disease (Table 1 (1-5)).

Clinical Diagnosis

many patients with celiac disease have diarrhea, borborygmus, abdominal pain, and weight loss (Table 2 (6-11)). However, the disease can affect several organ systems, including the skin, liver, nervous system, bones, reproductive system, and endocrine system. 12,13 Dermatitis herpetiformis (Figure 1), a pathognomonic skin eruption, occurs in 10 to 20 percent of patients with celiac disease. (14)

Because the small intestine can compensate if the degree of involvement is limited, many patients (up to 38 percent) are asymptomatic. (2,15) The disease is often diagnosed only through careful attention to clinical signs such as iron deficiency anemia or osteoporosis, through screening of patients at increased risk, or through other testing. One report found that up to 36 percent of patients with celiac disease had previously received a diagnosis of irritable bowel syndrome. (9) Common conditions that should be considered in the differential diagnosis are listed in Table 3. (10) a suggested diagnostic approach to patients with possible celiac disease is summarized in Figure 2.

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Diagnostic Tests

No single test has been universally accepted as the standard for diagnosing celiac disease. However, serologic testing and small bowel biopsy are highly sensitive and specific in making the diagnosis, particularly in patients with symptoms suggestive of celiac disease and in those at increased risk (e.g., those with a family history of the disease, those with an associated autoimmune disorder). (16) Diagnostic testing must be performed while the patient is on a diet that includes gluten-containing foods.

Patients with persistent gastrointestinal symptoms such as diarrhea, malabsorption, weight loss, abdominal pain, gas, and bloating should be evaluated for celiac disease. Diagnostic testing should also be considered in patients with premature osteopenia or osteoporosis, unexplained iron deficiency anemia, or unexplained liver abnormalities, and in high-risk patients with any of these findings or unexplained gastrointestinal symptoms (Table 46). Screening in asymptomatic patients is not recommended.
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