Management of osteoporosis in a pre-menopausal woman.

There is no agreed definition of osteoporosis in pre-menopausal women. The International Society for Clinical Densitometry recommends using Z-score, and women with Z-scores of -2.0 or lower should be defined as having a bone density that is 'below the expected range for age'. The diagnosis is more readily made in the presence of a low-trauma fracture. The relationship between low bone mineral density (BMD) in young pre-menopausal women and its associated fracture risk is not the same as in older women with a low BMD. Between 50% and 90% of pre-menopausal women will have an underlying secondary cause, the most common being eating disorders, anorexia nervosa and use of glucocorticoids. Management should focus on identifying the underlying cause and treating it where possible. The use of pharmacological therapy under other circumstances should be considered carefully. Women with only low BMD and no other risk factors probably require no pharmacological intervention. Those with low BMD and secondary causes or with a severely low BMD, or those who have fragility fractures, may require treatment with anti-resorptive agents, which can include oestrogen, bisphosphonates, calcitonin, calcitriol or anabolic therapy with teriparatide. Selective oestrogen receptor modulators (SERMs) should be avoided as they cause further bone loss in menstruating women. Alendronate and risedronate have been licensed for use in glucocorticoid-induced osteoporosis. These drugs accumulate in the human skeleton and have been shown to cross the placenta and accumulate in newborn rats. The effects on human pregnancy are unclear, although normal pregnancies have been reported. Pre-menopausal women with osteoporosis should be followed up until the BMD is stable, which can usually be ascertained by follow-up scans at 18-36-month intervals.