Evaluation of bone mineral density and bone turnover markers in patients with ankylosing spondylitis

Abstract

Objective: Ankylosing spondylitis (AS) is a complex, potentially debilitating disease that is insidious in onset, progressing to deformity in spine over several years. Men are more often affected than women. Osteoporosis and vertebral fractures are now well recognized features in patients with advanced AS. The aim of this study was to compare BMD of lateral lumbar spine and hip in male patients with AS and control group. Methods: 27 consecutive AS patients with a mean disease duration of 9.9 y and 23 age, height and weight-matched healthy controls were recruited for the study. The mean age of the AS patients was 39.31±12.13 and the mean age of the control group was 40.90±8.41. In both patients and control groups, BMD was evaluated for the lumbar spine and hip. Serum osteocalcin and urinary N-telopeptide (NTx) were measured as bone turnover markers in both patients and control groups. Results: Osteoporosis was detected 1(4.3%) of control group and in 5(18.5%) of AS patients. The femoral neck and femur total T-scores, lateral lumbar 3 T-score values were significantly lower in AS patients compared with the control group (p=0.035 and p=0.03, p=0.001, successively). Osteocalcin and NTx levels were significantly higher in patients with AS compared with the control group (p<0.05). Conclusion: The incidence of osteoporosis is high in AS patients compare control group. The monitoring of bone turnover markers may help to prognostic of development osteoporosis in AS patients. The risk of vertebral fractures can increase in AS patients with osteoporosis. The fractures of AS patients are atypical that may be caused morbidity and in some case mortality. The patients with AS must be assessed for osteoporosis and must be treated for osteoporosis, so severe complications such as fractures can be prevented in AS.