Determination of bone mineral density (BMD) is essential in the management of osteoporosis, including initial screening and diagnosis, treatment planning, and follow-up of disease progression and treatment response. Dual X-ray absorptiometry (DXA) is generally considered the “gold standard” for the assessment of BMD and estimation of fracture risk. Other approaches, such as quantitative ultrasound or computed tomography, are used less often. DXA BMD results are usually expressed in relation to the mean value for health young adults (T score) or to the mean value for individuals of the same age, race, and sex (Z score). BMD may be used in combination with clinical factors such as age, sex, body weight, family history, and medication use to calculate an estimated 10-year risk of fractures, which may be used in deciding whether osteoporosis therapy should be considered. Follow-up examinations are important to monitor disease progression and response to treatment. The timing of follow-up examinations depends on factors such as baseline BMD, precision of BMD assessment, and the expected rate of bone loss. This article reviews the rationale for BMD testing, the most common methods for evaluating BMD, and the manner in which densitometry results are used to diagnose osteoporosis and evaluate response to therapy.
At the conclusion of this activity, readers should be able to:
- Discuss osteoporosis risk factors and the potential clinical consequences of unrecognized osteoporosis.
- Summarize guideline recommendations for osteoporosis screening and diagnosis, including preferred bone densitometry devices, diagnostic criteria, and follow-up intervals.
- Explain how a fracture risk score is calculated, and how this score is used in osteoporosis diagnosis and treatment.
Categories: X-Ray/Radiography, Digital Radiography