Oestrogen, the prevention of bone loss and osteoporosis

There is overwhelming evidence that oestrogen can prevent bone loss and there is less good but convincing evidence that oestrogen prevents fractures. Oestrogen use of between 5 and 10 years is associated with a 50% reduction in risk of fracture. There is good evidence that in established osteoporosis, oestrogen prevents further bone loss and reduces the incidence of fractures. Oestrogen use leads to lasting skeletal benefits and will prevent bone loss at whatever age it is started. Prior to fracture there are no symptoms associated with osteoporosis and few patients will be diagnosed at a time when effective treatment could be instigated. It is apparent that the risk of developing osteoporosis cannot be deduced from clinical data alone and bone mineral measurements provide the single best test for future risk. Bone mass can be measured directly and there is no need for guess work. The most important potential application for oestrogen is in preventive therapy, and the efficient use of oestrogen in this situation depends upon the diagnosis of low bone mass. Who to treat remains the issue. For any age group the median value of bone density and a range of percentiles can be generated, thus facilitating therapeutic decisions.