Bone mass and gastrointestinal disease.

Several gastrointestinal and liver diseases impair the absorption of calcium, phosphate, and/or vitamin D, and are associated with an increased incidence of bone disease. Changes in bone mineral density (BMD) using dual-energy X-ray absorptiomety (DXA) have been best studied in the malabsorptive disorder, celiac disease. Celiac disease is an inflammatory condition of the small intestine triggered by ingesting gluten present in wheat, rye, or barley. Chronic inflammation leads to intestinal atrophy and nutrient malabsorption. The disease affects the proximal small bowel; the site where calcium is best absorbed. About 70% of adults with celiac disease have abnormally low BMD values. Treatment with a gluten-free diet increases BMD, but not to normal values. As celiac disease may not be detected until adult life, the failure to reach normal BMD on a gluten-free diet can be explained, at least in part, by the failure to reach peak bone mass. All individuals with malabsorptive disorders should be screened for secondary bone disease. The development of easier and less expensive methods to assess BMD will facilitate screening those at risk for bone disease.