Prevention and treatment of osteoporosis require sensitive and specific assays of bone turnover. Presently, serum or urinary assessments are used. However, the development of other procedures that are more patient-convenient, non-invasive and cost-efficient would significantly facilitate a clinician's ability to determine bone turnover. The objective of this application is to determine the feasibility of using saliva for this measurement. We will compare serum, urinary and salivary levels in 50 pre- and 50 post-menopausal women. Markers to be measured are bone alkaline phosphatase, osteocalcin, procollagen type propepties hydroxypyridinium crosslinks of collagen and crosslinked collagen telopeptides. Collection of saliva, serum and urine will be done at a single visit. We expect to observe reasonable good correlation between serum and saliva levels and poorer correlation between urine and saliva levels.