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.