Urinary Bone Turnover Markers as Target Indicators for Monitoring Bisphosphonate Drug Treatment in the Management of Osteoporosis

Background: Osteoporosis is a debilitating disease characterized by bone micro-architecture degradation contributing to fragility fractures. Currently, determining bone mineral density (BMD) via dual-energy X-ray absorptiometry (DXA) is the most reliable form of diagnosing osteoporosis and managing pharmacological treatment regimens. However, changes in BMD occur slowly (i.e., several months) and DXA does not reflect the metabolic rate of bone turnover. Alternatively, biochemical bone turnover markers are metabolic indicators released into serum and/or urine, and their quantity reflects the metabolic activity of bone. bone turnover markers show a rapid response following antiresorptive drug administration, and enzyme-linked immunosorbent assays (ELISA) have been established and used in clinical trials to help assess and predict fracture risk independent of BMD. Objective: This review highlights various established bone turnover markers that have found utility in the clinic as reliable and standardized indicators of bone turnover, with attention to those used to assess efficacy of bisphosphonate drug therapy - particularly in monitoring medication adherence in patients with postmenopausal osteoporosis. Results: We posit that the use of urinary bone turnover markers values determined by immunoassay or ELISA at routine clinic visits might serve as valuable feedback to healthcare professionals and patients to help monitor the efficacy and adherence of bisphosphonate therapy and disease progression. Conclusion: Our belief is that when assessed in combination with an algorithm of independent risk factors, measuring urinary bone turnover markers using a point of care kit may find utility in the osteoporosis clinic as an accessible, non-invasive and cost-effective alternative for the routine assessment of efficacy of bisphosphonate therapies.