The skeleton is active organ that is remodeling (rebuilding) throughout lifetime. It is important to supply body with enough calcium and vitamin D to be able to constantly rebuild and repair skeleton. Physical exercise also helps preserve healthy skeleton. Male and female sex hormones play important role in skeletal metabolism and lack leads to weakening of bones (this why elderly individuals have more problems with bones than younger ones). Disorders of bone metabolism are common and individuals at risk need to be tested for them.