Results are generally scored by two measures, the T-score and the Z-score. Scores indicate the amount one's bone mineral<unk>  varies from the mean. Negative scores indicate lower<unk> , and positive scores indicate higher. Less than 0.5% of patients who underwent DXA-scanning were found to have a T- or Z-score of more than +4.0, often the cause of an unusually high bone mass (HBM) and associated with mild skeletal dysplasia and the inability to float in water. T-score The T-score is the relevant measure when screening for osteoporosis. It is the bone mineral<unk>  (BMD) at the site when compared to the young normal reference mean. It is a comparison of a patient's BMD to that of a healthy 30-year-old. The US standard is to use data for a 30-year-old of the same sex and ethnicity, but the WHO recommends using data for a 30-year-old white female for everyone. Values for 30-year-olds are used in post-menopausal women and men over age 50 because they better predict risk of future fracture. The criteria of the World Health Organization are: * Normal is a T-score of −1.0 or higher * Osteopenia is defined as between −1.0 and −2.5 * Osteoporosis is defined as −2.5 or lower, meaning a<unk>  that is two and a half standard deviations below the mean of a 30-year-old man/woman. + Hip fractures per 1000 patient-years WHO category Age 50–64 Age > 64 Overall Normal 5.3 9.4 6.6 Osteopenia 11.4 19.6 15.7 Osteoporosis 22.4 46.6 40.6 Z-score The Z-score for<unk>  is the comparison to the age-matched normal and is usually used in cases of severe osteoporosis. This is the standard score or number of standard deviations a patient's BMD differs from the average BMD of their age, sex, and ethnicity. This value is used in premenopausal women, men under the age of 50, and in children and adolescents. It is most useful when the score is less than 2 standard deviations below this normal. In this setting, it is helpful to scrutinize for coexisting illnesses or treatments that may contribute to osteoporosis such as glucocorticoid therapy, hyperparathyroidism, or alcoholism.
Bone density
Body composition
Bone age
Peak bone mass
Lean body mass
Body fat percentage
Waist–hip ratio
Human height