From the Guidelines
The primary diagnostic test for osteoporosis and osteopenia is a dual-energy X-ray absorptiometry (DXA or DEXA) scan, which measures bone density at the lumbar spine, total hip, femoral neck, and one-third radius, with results reported as T-scores to determine the presence of osteoporosis or osteopenia 1.
Diagnostic Tests for Osteoporosis and Osteopenia
The DXA scan is a non-invasive test that takes about 10-15 minutes to complete and is recommended for women 65 and older, men 70 and older, or earlier for those with risk factors such as fractures, certain medications, or medical conditions that affect bone health 1.
Key Points to Consider
- DXA BMD measurement should be performed at the lumbar spine, total hip, femoral neck, and, if indicated, one-third radius 1.
- Osteoporosis is diagnosed based on a T-score of − 2.5 or lower in the lumbar spine, femoral neck, total hip, or one-third radius, with the lowest T-score at any of these measured sites used for diagnosis 1.
- Some societies presume a diagnosis of osteoporosis in the presence of low-trauma major fracture (hip, spine, forearm, humerus, pelvis) 1.
- Blood tests may also be ordered to check calcium levels, vitamin D status, thyroid function, and other markers that might contribute to bone loss, including comprehensive metabolic panels, 25-hydroxyvitamin D levels, thyroid stimulating hormone (TSH), parathyroid hormone (PTH), and sometimes bone turnover markers like N-telopeptide (NTx) or C-telopeptide (CTx) 1.
Additional Tests
For some patients, especially men or younger individuals with unexplained bone loss, additional tests might include testosterone levels, estrogen levels, or 24-hour urine calcium measurements to determine if bone loss is occurring due to a secondary cause that needs specific treatment beyond standard osteoporosis medications 1.
Follow-up and Monitoring
Follow-up DXA scans are recommended as indicated, depending on clinical circumstances, and should ideally be conducted in the same facility with the same DXA system, if the acquisition, analysis, and interpretation adhere to recommended standards 1. The frequency of BMD testing in clinical practice may be influenced by the patient’s clinical state, national clinical guidelines, cost, and reimbursement, with suggested intervals between BMD testing typically ranging from 1-5 years after starting or changing therapy 1.
From the Research
Diagnostic Procedures for Osteoporosis and Osteopenia
- Dual-energy X-ray absorptiometry (DXA) is considered the best method for measuring bone density and diagnosing osteoporosis 2, 3, 4, 5
- DXA scans can be used to measure bone mineral density at various sites, including the lumbar spine and femoral neck 2, 3
- A T-score of -2.5 or less on a DXA scan is diagnostic of osteoporosis, while a T-score between -1 and -2.5 indicates osteopenia 3, 5
- Vertebral fractures are generally considered diagnostic of osteoporosis, even if spine BMD values are not in the osteoporotic range 3
- Quantitative ultrasound (QUS) scanners can be used as a pre-screening tool for osteoporosis, but require subsequent diagnosis confirmation by DXA evaluation 4
- Laboratory tests, such as measurements of 25-hydroxyvitamin D, serum and urine calcium, and renal function, can be used to evaluate secondary osteoporosis 6
Indications for Diagnostic Testing
- DXA scans should be considered for women 65 years and older, or postmenopausal women with clinical risk factors 5
- Men 70 years and older, or men with clinical risk factors, may also benefit from DXA scans 5
- Patients with a high risk of fracture, or those with a history of fragility fractures, should be considered for diagnostic testing 3, 5
Limitations and Considerations
- DXA scans have limitations, including the use of ionizing radiation, high costs, and limited availability 4
- QUS scanners are a cheaper and more portable alternative, but require subsequent DXA evaluation for diagnosis confirmation 4
- Laboratory tests may be necessary to evaluate secondary osteoporosis and guide treatment decisions 6