Osteoporosis is a thinning of bone caused by the loss of minerals in the body. Calcium is the primary mineral that is lost. The bone thinning can lead to fractures of the wrist, hip, or to the development of the characteristic "Dowager's hump" often seen in individuals as they age. Osteoporosis can also lead to the collapse of vertebrae in the spine so that people "shrink", or lose height.
It is normal for bone to be constantly rebuilding itself. Many of us think of bone as a hard substance that grows when we are young and when we reach our maximum height, it stays the same. In reality, your body is constantly taking calcium from the bone and rebuilding bone. We don't feel it and we certainly can't see it. In children and adolescents, our bodies build more bone than they lose. In older adults, the reverse is true - we lose more than we build.
The goal in aging and managing our health is to minimize bone loss in our bodies.