Osteodensitometry in irritable bowel syndrome

Introduction: Previous studies have found a low grade inflammation maintained by cytokine producing T-cells and mast cells in the bowel mucosa of patients with irritable bowel syndrome (IBS). The level of TNF-α, IL-1β and IL-6 is higher in IBS than in healthy controls. These cytokines activate osteoclasts and thus stimulate bone resorption through the RANK/RANK-L/OPG system, as it has been observed in patients with inflammatory bowel disease (IBD; Crohn's disease and ulcerative colitis). Our aim was to investigate if the bone mineral density of IBS patients approaches that of IBD patients and if it differs from that of healthy controls. Methods: We compared the bone mineral density of 26 IBS patients (IBS₁ group) with 26 sex- and age matched IBD control patients, and 39 IBS patients (IBS₂ group) with 39 sex- and age matched healthy controls. Bone density measurements were performed by dual-energy X-ray absorptiometry (DEXA) at the lumbar spine and the femoral neck. Results were expressed as bone mineral density (BMD), T- and Z-scores. Results: Bone density values of the IBS₁ group: lumbar BMD: 0.99±0.17, T-score: –0.73±1.50, Z-score: –0.15±1.50; femoral BMD: 0.84±0.11, T-score: –0.40±0.79, Z-score: 0.32±0.89. Results of the IBD group: lumbar BMD: 0.93±0.11, T-score: –1.21±1.05, Z-score: –0.62± 1.07; femoral BMD: 0.71±0.15, T-score: –1.30±1.22, Z-score: –0.68± 1.15. There is no significant difference between the densities at the lumbar spine, but the femoral densities are significantly lower in the IBD group than in the IBS₁ group (p<0.05). Values of the IBS₂ group: lumbar BMD: 0.96±0.15, T-score: –0.90±1.38, Z-score: –0.07±1.32; femoral BMD: 0.80±0.13, T-score: –0.67±0.94, Z-score: 0.25±0.92. Values of the normal control group: lumbar BMD: 0.96±0.11, T-score: –1.44±0.99, Z-score: –0.32±1.01; femoral BMD: 0.78±0.11, T-score: –0.72±0.91, Z-score: 0.15±0.94. There was no significant difference between the results of IBS patients and healthy controls. Conclusions: According to our results bone density of patients with irritable bowel syndrome does not differ from that of the healthy population, and the bone density at the femoral neck of patients with inflammatory bowel disease is significantly lower than that of IBS patients.