Bone Density and Bone Metabolism in Patients with Inflammatory Bowel Disease

BACKGROUND/AIMS: Patients with inflammatory bowel disease (IBD) are at high risk for low bone mineral density (BMD). This study aimed to evaluate BMD in IBD patients and its relationship with bone metabolism in a group of Iranian patients. PATIENTS AND METHODS: A cross-sectional study was conducted on patients with IBD to assess BMD status and serum biochemical factors. After getting the demographic data from 200 patients, they were screened using dual-energy X-ray absorptiometry of the lumbar spine (L2–L4) and femoral neck for BMD status. Serum levels of calcium, phosphate, alkaline phosphatase (ALP), and 25-hydroxyvitamin D (25-OH vitamin D) were measured to assess the bone metabolism status. RESULTS: Two hundred patients with IBD were enrolled in the study. One hundred and eighty three (91.5%) patients were identified as having ulcerative colitis (UC) and 17 (8.5%) as having Crohn's disease (CD). Based on the lumbar and femoral neck bone mass densitometry, 148 (74.4%) patients had low BMD at either lumbar spine or femoral neck. Of these, 100 patients (50.3%) were osteopenic and 48 patients (24.1%) were osteoporotic. A 58.6% and 61% of patients with UC had low BMD in the lumbar and femoral neck, respectively. These results for those with CD were 76.5% and 70.6%, respectively. The mean of femoral neck and lumbar T-scores in patients with UC were -1.14 and -1.38, and in patients with CD were -1.24 and -1.47, respectively (P > 0.05). The mean (±SD) levels for calcium (Ca) in UC and CD were in the normal range. The mean (±SD) levels of ALP and 25-OH vitamin D in both the groups were in the normal range, and in comparison between groups (UC and CD), no significant differences were observed (P = 0.20 for ALP and P = 0.44 for 25-OH vitamin D). In the assessment of correlation between biochemical markers and BMD, an inverse correlation between lumbar T-score and ALP or 25-OH vitamin D only in patients with UC was observed. CONCLUSIONS: The high prevalence of low BMD in the Iranian population with IBD needs attention. The subclinical vitamin D deficiency may contribute to bone loss in IBD patients, which is more pronounced in patients with UC in this study because of the small population of patients with CD.