Why We Need To Look AT Bone Quality...Not Just Bone Quantity (DXA Scans)
Over the past thirty years, the use of medications for the treatment of osteoporosis has gradually increased. Although it has been well documented that these drugs limit osteoclastic bone resorption, increase bone mineral density, and reduce spinal fractures (although they are much less effective at reducing hip fractures), there are many safety concerns.
Bisphosphonates work by reducing resorption which, when excessive or in the absence of equivalent bone formation by osteoblast cells, leads to bone loss. But osteoclastic resorption is essential for bone health, and over-suppression has been shown to increase accumulation of microdamage, impair mineralization, increase brittleness, and reduce the general biomechanical competence of bone.
The currently prescribed bisphosphonates have undesirable side effects, including gastrointestinal pain, muscle pain, bone and joint pain, esophagitis, stomach ulcerations and atrial fibrillation. There are also concerns that long-term bisphosphonate and denosumab (Prolia) therapy can over-suppress bone turnover and lead to increased risk for osteonecrosis of the jaw (ONJ), spontaneous mid-shaft femur fractures, and overall fracture rate.
It has also become evident that the increase in bone mineral density seen with drug therapy for osteoporosis is only weakly associated to overall fracture risk reduction and only slightly improves bone strength. Despite these facts, physicians tend to rely only on bone mineral density (quantity) DXA testing and have been slow to grasp the importance of assessing bone quality-related laboratory biomarkers when assessing the causes of bone fragility.
How do we do this? How do we look into the intricate physiology of an individual and determine what they need to help them improve bone quality...not just bone quantity? The answer is laboratory THERAPEUTIC TARGETS.
There are numerous laboratory tests that are correlated in some manner or another with excessive bone loss and/or increased risk for breaking a bone. These tests can be used, not as direct indicators of bone quality or strength, but as indirect indicators or surrogates of poor bone health and heightened fracture risk. By focusing upon these lab tests they can be targets to improve upon and thus increase the quality and strength of bone. Just as an elite athlete would target the bull's eye to improve his or her skills as a competitive marksman, you can target lab tests to improve therapeutic outcome.
In my next blog, I will write about a fascinating biomarker called osteocalcin and how it can be used to diagnose the cause of bone loss and help guide therapeutic protocol.*
*These statements have not been evaluated by
the Food and Drug Administration and are
not intended to diagnose, treat,
cure, or prevent any disease.