In adults, the turnover rate is still 3 to 5 percent yearly. After we reach adulthood, remodeling continues, whether it is healing that occurs after a fracture, or an ever-changing equilibrium of calcium being added and taken away to maintain strength. There are many checks and balances in our skeletal system. Hormones such as parathyroid and vitamins such as vitamin D control the level of calcium in bone. Cortisone from the adrenal glands and medicines containing cortisone drugs cause loss of calcium from bones.
Growth hormone increases the collagen supporting tissue of bone.
What this adds up to is that the constant remodeling of bone is the sum of the interaction of hormones and mechanical stresses of life on the basic growth centers of bones. It is a constant, dynamic equilibrium. Osteoporosis is the excessive loss of calcium and matrix of bone. It is sometimes noticed because the person shows reduced height or a humping of the back, or suffers from low back pain. Dr. Bevra Hahn and her husband, Dr. Theodore Hahn, medical researchers of osteoporosis for many years, point out that bone loss begins as early as twenty years old and is over three times greater in women than in men.