Evaluation of bone mineral density, bone turnover markers, the OPG/RANKL system and sTNF-RI in Crohn's disease]

Patients with Crohn's disease are at risk of developing osteoporosis, a disease in which the inflammatory process seems to be gaining importance. We performed a cross-sectional study to evaluate bone metabolism, osteoclastogenic factors [receptor activator of NF-kB ligand (RANK-L) and osteoprotegerin (OPG)] and soluble tumor necrosis factor-α receptor I (sTNF-RI) in patients with Crohn's disease and to correlate the findings with the degree of disease activity.Sixty-four patients with Crohn's disease from the province of Granada (Spain) were included in this study. Bone mineral density (BMD) was studied through dual X-ray absorptiometry. Immunoassay was used to assess markers of bone formation [bone alkaline phosphatase (bALP) and osteocalcin (OC)] and bone resorption [tartrate resistant acid phosphatase (TRAP) and carboxyterminal telopeptide of type I procollagen (CTX)] as well as RANKL, OPG and sTNF-RI.The percentage of patients with a Z-score ≤-2 in the femoral neck or lumbar spine was 20.3% and was higher in patients with active disease, although this difference was not significant. This percentage was only higher in patients receiving corticosteroids (11.1 vs. 9.1%; P=.001). Patients with the highest disease activity had higher TRAP levels. No significant differences were found in BMD but significant differences were found in TRAP levels with respect to C-reactive protein concentrations. No association was found between levels of OPG, RANKL and sTNF-RI and BMD or disease activity.A substantial proportion of our patients had low BMD. Levels of bone turnover markers suggested higher bone resorption, possibly in relation to disease activity, without a compensatory increase in bone formation.