[Bone and bone related biochemical examinations. Bone and collagen related metabolites. Measurement and clinical role of OPG].

Osteoprotegerin (OPG) has been identified as a novel cytokine that specifically inhibits osteoclastogenesis. OPG acts as a soluble decoy receptor that inhibits the binding of receptor activator of NF-kappaB ligand (RANKL) to its receptor RANK and thus inhibits the proliferation and activation of osteoclasts. Human serum OPG can now be easily measured using a sandwich-type ELISA kit, and the roles of OPG in various diseases have been revealed by clinical studies. These clinical studies have demonstrated that OPG plays an important role in not only metabolic bone diseases but also other diseases such as coronary artery disease, vascular calcification, chronic renal failure and malignancy. Furthermore, OPG may be a useful and novel marker related to the progression or mechanisms of these diseases.