Osteoporosis is characterized by low bone mass with microarchitectural disruption and skeletal fragility that results in an increased risk of fracture. The diagnosis has traditionally been established by bone densitometry, which is generally reported in terms of standard deviations (SD) from mean values in young adults (T score). The World Health Organization (WHO) has defined normal bone mineral density (BMD) for women as a value within one SD of the young adult mean. Values 2.5 SD (T score -2.5) or more below the mean are defined as osteoporosis. The WHO has developed a computerized model (FRAX) that predicts the 10-year probability of hip fracture based on clinical risk factors and BMD at the femoral neck.

The results of a randomized, placebo-controlled trial of calcium and vitamin D supplements in more than 36,000 postmenopausal women, conducted as part of the Women’s Health Initiative (RD Jackson et al. N Engl J Med 2006; 354:669), have been misinterpreted by some patients to mean that they should stop taking such supplements.

At the time of recruitment, the participants in this study had an average daily calcium intake of 1100-1200 mg. They were randomized to take either 1000 mg of calcium carbonate plus 400 IU of vitamin D₃ or a placebo for an average of 7 years. Both groups were permitted to take calcium and vitamin D supplements on their own as well. In the intention-to-treat population, the study supplements increased hip bone density but did not decrease the incidence of hip fractures. The subgroup of women who adhered to the protocol and actually took the study supplements showed a significant reduction in hip fractures compared to the control group.

Men and women over age 50 should have a total calcium intake of about 1200 mg per day (Treat Guidel Med Lett 2005; 3:69). If they need a supplement to achieve that, calcium citrate is more expensive, but it offers some advantages over calcium carbonate: it can be taken without food, causes less GI disturbance and may be less likely to cause kidney stones.

With any calcium salt, vitamin D is necessary for optimal absorption. The recommended minimum daily requirement of vitamin D (vitamin D₃ is preferred) is 400 IU for people 50-70 years old and 600 IU for those over 70. But those infrequently exposed to the sun may need 800- 1000 IU of vitamin D daily, and many experts recommend 800 IU or more for all postmenopausal women.

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Many drugs are now marketed for treatment of postmenopausal osteoporosis, but questions remain about their use.

Many drugs are now marketed for treatment of post-menopausal osteoporosis (PD Delmas, Lancet 2002; 359:2018). Prevention of this disorder has been complicated by the news that hormone replacement therapy (HRT), which many women have been taking to prevent osteoporosis, increases the incidence of coronary heart disease and that of breast cancer, stroke and pulmonary embolism as well (Medical Letter 2002; 44:78).