Association between disease activity and osteocalcin, β-isomerized C-terminal telopeptides in SAPHO syndrome

Objective To investigate the relationship between disease activity and osteocalcin, β-isomerized C-terminal telopeptides(β-CTX)in SAPHO syndrome. Methods We studied 58 cases who were diagnosed as SAPHO syndrome. The following indices used to assess the activity of SAPHO were measured: Bath ankylosing spondylitis Disease activity index(BASDAI), Bath ankylosing spondylitis functional index(BASFI), visual analogue scale(VAS)pain and erythrocyte sedimentation rate(ESR), C-reactive protein(CRP), osteocalcin and β-CTX. The SAPHO patients were divided from two groups according to the disease activity. The relationships were analyzed with t-test and Pearson's test. Results The β-CTX of the active group(0.43 ±0.20)ng/ml was elevated than the stable group(0.23 ±0.09)ng/mL(t=-4.620, P=0.007). And there was no significant difference in the osteocalcin between the active group(2.7 ±1.0)μg/L and the stable group(2.4±1.0)μg/L(t=-1.169, P=0.820). There was no significant correlation between the serum osteocalcin and ESR or hypersensitive CRP(hs-CRP)(rESR=0.228, PESR=0.088; rhsCRP=-0.085, PhsCRP=0.528). And β-CTX level was related to the VAS(r=0.496, P<0.01), BASDAI(r=0.401, P=0.002)and BASFI(r=0.295,P=0.025). While no significant relationship between the osteocalcin and pain index was observed in our study. Conclusion The positive correlation between serum β-CTX and disease activity indicates significant bone absorption during the bone destroy process in SAPHO syndrome. Key words: Osteocalcin; Synovitis, acne, pustulosis, hyperostosis and osteitis syndrome; β-isomerized C-terminal telopeptides