Osteoporosis: integrating biomarkers and other diagnostic correlates into the management of bone fragility.

Bone health, characterized by its mass, density, and micro-architectural qualities, is maintained by a balanced system of remodeling. The lack of these qualities, caused by an uncoupling of the remodeling process, leads to bone fragility and an increased risk for fracture. The prime regulator of bone remodeling is the RANK/RANKL/OPG system. The common origin of both bone and immune stem cells is the key to understanding this system and its relationship to the transcription factor nuclear factor kappaB in bone loss and inflammation. Via this coupled osteo-immune relationship, a catabolic environment from heightened proinflammatory cytokine expression and/or a chronic antigen-induced activation of the immune system can initiate a switch-like diversion of osteoprogenitor-cell differentiation away from monocyte-macrophage and osteoblast cell formation and toward osteoclast and adipocyte formation. This disruption in bone homeostasis leads to increased fragility. Dietary and specific nutrient interventions can reduce inflammation and limit this diversion. Common laboratory biomarkers can be used to assess changes in body metabolism that affect bone health. This literature review offers practical information for applying effective strategic nutrition to fracture-risk individuals while monitoring metabolic change through serial testing of biomarkers. As examples, the clinician may recommend vitamin K and potassium to reduce hypercalciuria, _-lipoic acid and N-acetylcysteine to reduce the bone resorption marker N-telopeptide (N-Tx), and dehydroepiandrosterone (DHEA), whey, and milk basic protein (the basic protein fraction of whey) to increase insulin-like growth factor-1 (IGF-1) and create a more anabolic profile.