Osteoporosis: using 'bone markers' for diagnosis and monitoring.

Bone is continuously resorbed and formed in the process of remodeling. Osteoporosis results when bone loss is sufficient to cause increased risk of fracture. High rates of bone turnover can be identified by measuring biochemical byproducts of resorption and formation. Collagen crosslinks and associated peptides measured in urine are newly recognized markers for bone resorption. Bone-specific alkaline phosphatase and osteocalcin are serum markers for bone formation. The clinical utility of these new techniques is two-fold: to identify adults at high risk of osteoporosis so that preventive therapy can be instituted, and to provide noninvasive, sensitive tools for monitoring clinical course and effect of therapy.