Who should be screened?
Screening is generally performed with a clinical evaluation and a dual-energy x-ray absorptiometry (DXA) scan of BMD. Measurement of BMD is generally recommended for screening all women ≥ 65 years and those < 65 years whose 10-year risk of fracture is equivalent to that of a 65-year-old White woman (see “Assessment of fracture risk” later in the article). For men, the US Preventive Services Task Force recommends screening those with a prior fracture or a secondary risk factor for disease.5 However, the National Osteoporosis Foundation recommends screening all men ≥ 70 years and those 50 to 69 years whose risk profile shows heightened risk.1,4
DXA of the spine and hip is preferred; the distal one-third of the radius (termed “33% radius”) of the nondominant arm can be used when spine and hip BMD cannot be interpreted because of bone changes from the disease process or artifacts, or in certain diseases in which the wrist region shows the earliest change (eg, primary hyperparathyroidism).6,7
Clinical evaluation includes a detailed history, physical examination, laboratory screening, and assessment for risk of fracture.
❚ History. Explore the presence of risk factors, including fractures in adulthood, falls, medication use, alcohol and tobacco use, family history of osteoporosis, and chronic disease.6,7
❚ Physical exam. Assess height, including any loss (> 1.5 in) since the patient’s second or third decade of life; kyphosis; frailty; and balance and mobility problems.4,6,7
❚ Laboratory and imaging studies. Perform basic laboratory testing when DXA is abnormal, including thyroid function, serum calcium, and renal function.6,12 Radiography of the lateral spine might be necessary, especially when there is kyphosis or loss of height. Assess for vertebral fracture, using lateral spine radiography, when vertebral involvement is suspected.6,7
❚ Assessment of fracture risk. Fracture risk can be assessed with any of a number of tools, including:
- Simplified Calculated Osteoporosis Risk Estimation (SCORE): www.medicalalgorithms.com/simplified-calculated-osteoporosis-risk-estimation-tool
- Osteoporosis Risk Assessment Instrument (ORAI): www.physio-pedia.com/The_Osteoporosis_Risk_Assessment_Instrument_(ORAI)
- Osteoporosis Index of Risk (OSIRIS): https://www.tandfonline.com/doi/abs/10.1080/gye.16.3.245.250?journalCode=igye20
- Osteoporosis Self-Assessment Tool (OST): www.ncbi.nlm.nih.gov/books/NBK45516/figure/ch10.f2/
- FRAX tool5: www.sheffield.ac.uk/FRAX.
The FRAX tool is widely used. It assesses a patient’s 10-year risk of fracture.
Diagnosis is based on these criteria
Diagnosis of osteoporosis is based on any 1 or more of the following criteria6:
- a history of fragility fracture not explained by metabolic bone disease
- T-score ≤ –2.5 (lumbar, hip, femoral neck, or 33% radius)
- a nation-specific FRAX score (in the absence of access to DXA).
❚ Secondary disease. Patients in whom secondary osteoporosis is suspected should undergo laboratory investigation to ascertain the cause; treatment of the underlying pathology might then be required. Evaluation for a secondary cause might include a complete blood count, comprehensive metabolic panel, protein electrophoresis and urinary protein electrophoresis (to rule out myeloproliferative and hematologic diseases), and tests of serum 25-hydroxyvitamin D, parathyroid hormone, serum calcium, alkaline phosphatase, 24-hour urinary calcium, sodium, and creatinine.6,7 Specialized testing for biochemical markers of bone turnover—so-called bone-turnover markers—can be considered as part of the initial evaluation and follow-up, although the tests are not recommended by the US Preventive Services Task Force (see “Monitoring the efficacy of treatment,” later in the article, for more information about these markers).6
Although BMD by DXA remains the gold standard in screening for and diagnosing osteoporosis, a high rate of fracture is seen in patients with certain diseases, such as type 2 diabetes and ankylosing spondylitis, who have a nonosteoporotic low T-score. This raises concerns about the usefulness of BMD for diagnosing osteoporosis in patients who have one of these diseases.13-16
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❚ Trabecular bone score (TBS), a surrogate bone-quality measure that is calculated based on the spine DXA image, has recently been introduced in clinical practice, and can be used to predict fracture risk in conjunction with BMD assessment by DXA and the FRAX score.17 TBS provides an indirect index of the trabecular microarchitecture using pixel gray-level variation in lumbar spine DXA images.18 Three categories of TBS (≤ 1.200, degraded microarchitecture; 1.200-1.350, partially degraded microarchitecture; and > 1.350, normal microarchitecture) have been reported to correspond with a T-score of, respectively, ≤ −2.5; −2.5 to −1.0; and > −1.0.18 TBS can be used only in patients with a body mass index of 15 to 37.5.19,20
There is no recommendation for monitoring bone quality using TBS after osteoporosis treatment. Such monitoring is at the clinician’s discretion for appropriate patients who might not show a risk of fracture, based on BMD measurement.
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