Bone strength and density start to deteriorate from about 35 years old. The osteoclasts, which resorb old bone, start to become more active than the osteoblasts which deposit new bone. The rate of rebuilding fails to keep up with the rate of breakdown, resulting in osteoporosis. Large gaps appear in the trabecular bone as the honeycomb structure crumbles. The denser cortical bone is also affected.
Women are more at risk than men as they have smaller skeletons.
They experience a five to ten-year period of rapid bone loss at the menopause due to a fall in oestrogen levels. This is followed by a less rapid phase of age-related bone loss which men also experience. Screening Men and women who have already had a fracture after a minor fall are at risk of having another one. Back pain, particularly acute pain lasting for six to eight weeks in the over-50s, and height loss are also causes for concern. People worried about a risk of osteoporosis should be referred to a GP who might recommend a bone density measurement, helping both the doctor and patient to decide whether to prescribe or take preventative therapy.