 Bone mineral density BMD measurement using dual-energy x-ray absorptiometry DXA is the current gold standard for osteoporosis diagnosis and therapy monitoring. Like all quantitative tests, there is some variability in BMD results obtained when scanning a person more than once. As such, it is current clinical practice, based on the recommendation of the International Society for Clinical Densitometry, that each technologist perform a precision assessment. This approach consists of scanning 30 people twice; the data from which allow determination of what constitutes a real difference in BMD with 95 confidence. A precision assessment typically evaluates a specific clinics population, using the age range and genders seen at that clinic. However men generally have larger, but often more arthritic, bones than women which may impact the precision results. Therefore, it is possible that gender-specific precision values should be used in clinical practice, however this issue has never been investigated. 