Biomarkers of Bone Turnover: Molecular Approaches and Clinical Relevance

Osteoporosis, a disease characterized by low bone mass and deterioration of bone microarchitecture, leads to increased fragility and susceptibility to fracture. It is an important public health problem of the elderly and it is expected to rise with an increased life expectancy in the next years. Bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) is considered as the gold standard of bone status assessment despite the associated limitations. In recent years great progress has been made in the identification and characterization of biomarkers to aid the knowledge of metabolic bone disease and within the last years, a large number of new bone turnover markers (BTM) with increased specificity and sensitivity have been developed. BTM of formation and desorption are released during the process of bone remodeling. Bone biomarkers can be a great tool for the diagnosis of osteoporosis, but their use in clinical practice is limited because there are subjected to various preanalytical and analytical variations. Also, BTM are frequently used to provide valid information about the effectiveness of osteoporosis treatment (antiresorptive or bone formation therapies) although they are not useful alone to estimate bone loss. In this review, conventional and novel BTMs, their use and limitations into clinical practice, available diagnostic methods and current recommendations are discussed.

Keywords: Bone, Bone biomarkers, Bone desorption, Bone disorders, Bone formation, Bone loss, Bone metabolism, Bone mineral density, Bone turnover, Collagen, Fracture, Monitoring of treatment, Osteoblast, Osteoclast, Osteocyte, Osteoporosis, Prediction of fractures, Stability, Standardization, Variability.