Bone metabolism is very active through the whole life. Process is called "bone remodelation" and managed by bone cells - osteoclasts (bone resorption), osteoblasts (bone formation) and osteocytes (regulation of the whole process). Decrease of the oestrogen production after menopause leads to the primary, postmenopausal osteoporosis. The domination of resorption in older age leads to osteoporosis from involution.
Very common is secondary osteoporosis, connected to many diseases, rheumatic arthritis, chronic systemic inflammation, chronic renal disease or long-term glucocorticoid treatment, e.g.