Your body needs the minerals calcium and phosphate to make and keep healthy bones.
During your life, your body continues to both reabsorb old bone and create new bone.
As long as your body has a good balance of new and old bone, your bones stay healthy and strong.
Bone loss occurs when more old bone is reabsorbed than new bone is created.
Sometimes bone loss occurs without any known cause. Other times, bone loss and thin bones run in families. In general, white, elderly women are the most likely to have bone loss.
Brittle, fragile bones can be caused by anything that makes your body destroy too much bone, or keeps your body from making enough bone.
Weak bones can break easily, even without an obvious injury.
Aging and bone loss
As you age, your body may reabsorb calcium and phosphate from your bones instead of keeping these minerals in your bones. This makes your bones weaker. When this process reaches a certain stage, it is called osteoporosis.
Lewiecki EM. In the clinic. Osteoporosis. Ann Intern Med. 2011 Jul 5;155(1):ITC1-1-15; quiz ITC1-16.
National Osteoporosis Foundation. 2014 Clinician's Guide to Prevention and Treatment of Osteoporosis. April 1, 2014. http://nof.org/files/nof/public/content/file/2791/upload/919.pdf. Accessed on May 15, 2014.
C. Benjamin Ma, MD, Assistant Professor, Chief, Sports Medicine and Shoulder Service, UCSF Department of Orthopaedic Surgery. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.