Osteoporosis, the loss of mass of mineralized bone, is the most common metabolic bone disease. The depletion of minerals reduces the strength of the bone, and creates a high risk of fracture, which is the only symptom of osteoporosis. It is estimated that 250,000 hip fractures, 250,000 wrist fractures, and 500,000 vertebral fractures can be attributed to osteoporosis in the United States each year. The national cost of osteoporosis is estimated at over $6 billion annually. Early detection and treatment of osteoporosis can reduce the incidence of these fractures. To determine whether a screening program might be effective, the medical literature on bone mass assessment was reviewed. Bone mass measurements may be accomplished by a number of different techniques, all of which involve radiation. Quantitative computed tomography may be used. Another method is single-photon absorptiometry, which calculates bone mass by measuring the absorption of gamma rays. This technique has been greatly improved by the introduction of dual-photon absorptiometry, which measures gamma absorption at two different wavelengths to achieve greater precision. Likewise, dual-energy X-ray techniques have now been introduced for the same reason. Prospective studies have clearly indicated that women with greater bone mass loss have a greater risk of fracture. Estimates suggest that a single bone mass scan at menopause might reduce the lifetime risk of hip fracture from 10 to 8 percent, a reduction of 20 percent. However, these numbers are based on many assumptions. Prophylactic treatment involves estrogen replacement therapy for decades, and it is uncertain what levels of patient compliance could be expected. There have been no studies on the efficacy of prophylactic treatment based on early bone mass measurements. The development and preliminary trial of a screening program will be necessary before the public health impact of such a program can be determined. Until such data are available, screening should be limited to women with other indication of osteoporosis, such as an abnormal X-rays. (Consumer Summary produced by Reliance Medical Information, Inc.)