Relationship Between 25-(OH)D₃ And Disease Activity And Bone Metabolism In Ankylosing Spondylitis

ObjectivesTo evaluate the association between 25-(OH)D3 and the disease activity and bone metabolism in ankylosing spondylitis(AS). To determine what effect 25-(OH)D3 had exerted on the pathogenesis of AS.MethodFourty-two patients diagnosed as AS and 30 healthy subjects as control were included in this cohort study. The serum concentrations of 25-(OH)D3. the disease activity index (c-reactive protein, erythrocyte sedimentation rate, BASDA1. BASFI. BASMI) and the bone metabolism markers (N-MID osteocalcin. total procollagen type 1 amino-terminal peptide, C-telopeptides of type I collagen, parathormone and total calcium) were detected. The bone mineral density (BMD) of anterior and posterior lumber spines, the femoral neck, the Ward's triangle, the greater trochanter and the total hip were evaluated by dual energy x-ray absorptiometry. Compared the level of 25-(OH)D3, bone metabolism markers and BMD between the high disease activity AS group (16 subjects) and low disease activity AS group(26 subjects) according to the level of BASDAI. Compared the level of 25-(OH)D3. the disease activity index, bone metabolism markers between the osteoporosis/osteopenia group(19 subjects) and the normal BMD group(23 subjects) according to the total hip BMD values in AS patients. Evaluated the relationship between the level of 25-(OH)D3 and the disease activity index and bone metabolism marks and BMD in ankylosing spondylitis.ResultIn comparison with the control group, AS patients showed a significant reduction in 25-(OH)D3 (15.3±4.9 vs 20.1±4.2,p=0.012) and hip BMD (p<0.05), while the level ofβ-CTx was significantly higher (0.567±0.41 vs 0.363±0.13 ng/ml,p=0.037). In the high disease activity AS group,25-(OH)D3 levels (p= 0.041). lumbar BMD (p= 0.022), total hip BMD (p= 0.003) were significantly lower than the low disease activity AS group, and P-CTx levels were significantly higher (p=0.045). In the osteoporosis/-osteopenia group, the level of 25-(OH)D3 was lower in subjects than in the subjects with normal BMD (13.0±3.6 vs 17.1±5.1, p=0.007), while the levels ofβ-CTx. CRP (p=0.031), BASDAI (p=0.002)and BASFI (p=0.003)were higher than in the normal BMD group. Serum level of 25-(OH)D3 was negatively correlated with the CRP level and disease duration (r=-0.412, P=0.007; r=-0.329. p= 0.033). and had a positive correlation with the BMD of the lumbar, the Ward's triangle, the greater trochanter and the total hip BMD (r=0.452,p=0.003; r=0.385, p=0.012; r=0.357. p=0.020; r=0.393. p=0.010).ConclusionThe level of 25-(OH)D3 was significantly lower in AS patients, withβ-CTx was significantly increased and BMD decreased, and related to the disease activity and inflammatory markers. So the 25-(OH)D3 may play a role in the immuno-pathogenesis and monitoring disease activity in AS.