Abstract:

Objective To investigate the levels of serum cathepsin K（Cathe K） in osteoporosis diagnosis. Methods Bone mineral densities of lumbar spine and femoral neck were measured by dual energy X-ray. According to bone mineral densities,187 objects were classified into 63 cases of bone loss and 124 cases of osteoporosis. In osteoporosis group,32 cases' drug treatment efficacy was monitored. A total of 142 healthy subjects were enrolled as healthy control group. Enzyme-linked immunosorbent assay was used to determine serum Cathe K and tartrate-resistant acid phosphatase（TRAP）levels. The levels of osteocalcin（N-MID）,beta-collagen degradation product（β-crosslaps） and type Ⅰ procollagen N-terminal propeptide（PⅠNP）were determined by electrochemiluminescence immunoassay. According to ages,objects were classified into 35-45,46-55,56-65,66-70 and ≥71-year-old groups. Results For 35-45,46-55 and 56-65-year-old groups,the levels of serum Cathe K in osteoporosis group were higher than those in healthy control group（P<0.01）,but there was no statistical significance for 66-70 and ≥71-year-old groups between osteoporosis and healthy control groups （P>0.05）. For 35-45-year-old group,the level of serum Cathe K in bone loss group was higher than that in healthy control group（P<0.01）,and there was no statistical significance for the other age groups（P>0.05）. In the analysis of bone turnover markers for 45-65-year-old groups,the levels of serum Cathe K,PⅠNP,β-crosslaps,N-MID and TRAP in osteoporosis group were higher than those in bone loss and healthy control groups（P<0.05）. There was no statistical significance between bone loss and healthy control groups（P>0.05）. Serum β-crosslaps and Cathe K decreased in osteoporosis group after treatment for 3 months（P<0.05）. Conclusions Serum Cathe K can be used in the diagnosis and treatment monitoring of osteoporosis.

Key words: Cathepsin K, Osteoclast, Bone turnover markers, Osteoporosis