They are an important reservoir for minerals such as calcium. If the body's intake of the mineral calcium is too low, the bones release some of the calcium that is the main mineral in bone to make up the deficit. The loss of calcium weakens bones, however, making them more easily breakable. Various diseases that affect bones are discussed in more detail in Bone diseases . Other bone diseases and more information may be found by using the 'see also' references below.
Bone cancer is a serious complication of many other cancers .
Although cancer seldom originates on the hard outer part of bone, cancers that start elsewhere often become established on bone also. Cancers of the marrow that produce defective white blood cells are common, but these leukemias are considered blood cancers, not bone cancers. If part of the broken bone cuts through the skin , the break is an open, or compound, fracture. Broken bones grow back together if the broken parts stay close to each other, so physicians use various devices to hold bones in place while a break heals. The spongy-looking inner part of limb bones gives bone great strength combined with lightness, while the red marrow inside the bone produces blood cells.