The criteria of the World Health Organization are: 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 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. It is a comparison of a patient's BMD to that of a healthy 30-year-old. It is the bone mineral density (BMD) at the site when compared to the young normal reference mean. The T-score is the relevant measure when screening for osteoporosis. 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. Negative scores indicate lower bone density, and positive scores indicate higher. Scores indicate the amount one's bone mineral density varies from the mean. Results are generally scored by two measures, the T-score and the Z-score. The resulting comparison is used to determine the risk for fractures and the stage of osteoporosis (if any) in an individual.ДЄverage bone mineral density = BMC / W The density of these bones is then compared with an average index based on age, sex, and size. The DXA test works by measuring a specific bone or bones, usually the spine, hip, and wrist. Single energy X-ray absorptiometry (SEXA)ДXA is currently the most widely used, but quantitative ultrasound (QUS) has been described as a more cost-effective approach to measure bone density.Dual X-ray Absorptiometry and Laser (DXL).Dual-energy X-ray absorptiometry (DXA or DEXA).Most tests differ according to which bones are measured to determine the BMD result. While there are many different types of BMD tests, all are non-invasive. T-score: the number of standard deviations above or below the mean for a healthy 30-year-old adult of the same sex and ethnicity as the patient.Z-score: the number of standard deviations above or below the mean for the patient's age, sex and ethnicity.Results of the test are often reported in three terms: The usual response to either of these indications is consultation with a physician. Conditions found ДЄ bone density test may detect osteoporosis or osteopenia. Other considerations that are related to risk of low bone density and the need for a test include smoking habits, drinking habits, the long-term use of corticosteroid drugs, and a vitamin D deficiency. individuals with a history of eating disorders.when androgen deprivation therapy is being planned for prostate cancer.individuals being monitored to assess the response or efficacy of an approved osteoporosis drug therapy.individuals with primary hyperparathyroidism.individuals receiving, or planning to receive, long-term glucocorticoid ( steroid) therapy.individuals with vertebral abnormalities.previous bone fracture from minor trauma.The risk factors for low bone density and primary considerations for a bone density test include: Bone density measurements are used to screen people for osteoporosis risk and to identify those who might benefit from measures to improve bone strength.Д«one density tests are not recommended for people without risk factors for weak bones, which is more likely to result in unnecessary treatment rather than discovery of a true problem.

Fractures of the legs and pelvis due to falls are a significant public health problem, especially in elderly women, leading to much medical cost, inability to live independently and even risk of death. There is a statistical association between poor bone density and higher probability of fracture. The forearm may be scanned if the hip and lumbar spine are not accessible. Measurements are most commonly made over the lumbar spine and over the upper part of the hip. The measurement is painless and non-invasive and involves low radiation exposure. It is measured by a procedure called densitometry, often performed in the radiology or nuclear medicine departments of hospitals or clinics. Bone density measurement is used in clinical medicine as an indirect indicator of osteoporosis and fracture risk. The concept is of mass of mineral per volume of bone (relating to density in the physics sense), although clinically it is measured by proxy according to optical density per square centimetre of bone surface upon imaging. A scanner used to measure bone density using dual energy X-ray absorptiometryД«one density, or bone mineral density ( BMD), is the amount of bone mineral in bone tissue.

Bone density chart by age