Objectives: To explore the relationships between vitamin D intake, serum parathyroid hormone (PTH) and 25-hydroxyvitamin D (250HD) concentrations, and bone mineral density (BMD) in inflammatory bowel disease (IBD).
Setting: A university hospital clinic in Finland.
Subjects: One hundred and fifty randomly selected patients with IBD from the hospital register and 73 healthy controls.
Measurements: BMD of the lumbar spine and the proximal femur was measured with dual energy X-ray absorptiometry. Vitamin D intake and serum levels of 250HD and PTH were determined.
Results: The IBD patients had a lower serum 250HD concentration (28.4 [SD 12.0] nmol L-1) than the controls (36.1 [16.7] nmol L-1; P = 0.001), whereas no differences in the vitamin D intake or the serum PTH levels were found. The serum 250HD concentrations and the vitamin D intake of the patients with ulcerative colitis (n = 67) were similar to those of the Crohn's disease patients (n = 76). The patients with Crohn's disease of the small bowel had slightly, but not significantly, lower serum 250HD concentrations (25.6 [11.0] nmol L-1) than the other Crohn's disease patients (31.4 [14.3] nmol L-1; P = 0.061). In the IBD patients, the vitamin D intake and the serum 250HD and PTH concentrations were not associated with BMD.
Conclusions: Patients with IBD have lower serum levels of 250HD than healthy controls, but similar serum PTH concentrations and vitamin D intake. Vitamin D intake, and the serum levels of 250HD and PTH are not associated with BMD, and malabsorption is unlikely to be a major factor in the aetiology of bone loss in unselected IBD patients.