Celiac disease (gluten-sensitive enteropathy).

Celiac disease may be initially detected in either children or adults, even in the elderly. This small intestinal mucosal disorder is gluten-dependent and causes nutrient malabsorption, often with diarrhea and weight loss. Diagnosis depends on detection of typical biopsy changes in the proximal small bowel along with an unequivocal response to a gluten-free diet. Recurrent changes usually result from poor adherence to the gluten-free diet, sometimes intentional, or from consumption of unsuspected gluten sources. In others, the original diagnosis may not be correct (e.g., duodenal involvement with Crohn's disease) or another cause for symptoms may have supervened (e.g., collagenous colitis, functional bowel disease). Rarely, a complication may occur (e.g., collagenous sprue, lymphoma). In some, the gluten-dependent nature of the small bowel disorder was not initially documented and biopsy changes continued despite a gluten-free diet. These have a sprue-like intestinal disorder, also labeled unclassified sprue. This represents a small, but likely, heterogeneous group, and in these, intractable symptoms may be present and, in some, lymphoma is eventually diagnosed.