Posts Tagged ‘Bone Turnover’
Recently a patient asked me to review all osteoporosis medications for her to consider and choose from. We had already optimized her Calcium intake, 25-hydroxy Vitamin D level, Protein intake, Multiple Vitamins & Minerals, and Exercise program. These had all helped substantially, but not enough for her peace of mind. She feels that she needs osteoporosis medication too. Here they are:
Forteo (Teriparatide) increases the thickness of the struts making up spongy (cancellous) bone. Forteo is the only osteoporosis medication to do that. It also makes the hard outer shell (cortical bone) thicker. How? Forteo stimulates OsteoBlasts. They make bone matrix, the collagen protein that is more than 80% of bone.
Forteo also stimulates bone turnover. Healthy bone is constantly being resorbed and replaced. This allows bone to eliminate the micro-cracks that gradually accumulate with activity. Bone is strongest when it is a mixture of older more calcified (stiffer) material mixed thoroughly with younger less calcified (somewhat bendable) material. Cracks cannot enlarge. Strength is better. More force is required to fracture the bone.
Bisphosphonates accumulate in your bone. When OsteoClasts gobble up your bone, bisphosphonates are released into the Osteoclasts and disable or kill the Osteoclasts. This is great news when the problem is Osteoclasts Gone Wild. Bisphosphonates preserve bone by slowing down bone resorption. However, after a few months, bone formation by OsteoBlasts also slows down, resulting in slow bone turnover.
Moderate and balanced bone turnover is good. You repair microcracks in your bone when OsteoClasts resorb the bone around them and OsteoBlasts fill in the void with new bone matrix. A mix of new and old bone is far stronger than all old bone. Some OsteoClast activity is necessary to heal fractures, especially incomplete (stress) fractures. That is where long term bisphosphonates can be too much of a good thing.
Are your bones still good enough and just need to be maintained? Or have you fractured several times and need to rebuild your bones? Are Steroid Inhalers supressing your Osteoblasts – the cells that build new bone? (not good) Or have your Osteoclasts – the cells that eat away bone – gone wild (even worse) now that you are post-menopausal or an older guy?
Different problems require different classes of medication. Bisphosphonates, Hormone Replacement Therapy, Synthetic Estrogen Receptor Modifier – Evista, and RANK-Ligand Antibody – Prolia, are all Antiresorptives, which act in different ways. They slow down the Osteoclasts that have gone wild and are eating up the bone. The Anabolic, Forteo, stimulates the Osteoblasts that make new bone matrix. Antiresorptive and Anabolic are radically diferent actions.