What are the guidelines for managing low bone mineral density (BMD) in patients at risk of osteoporosis?

BMD Guidelines for Managing Low Bone Mineral Density

Initial Assessment and Screening

DXA of the lumbar spine and hip(s) is the gold standard imaging modality for BMD assessment and should be performed for all patients at risk of osteoporosis. 1

Who Should Be Screened

• All postmenopausal women ≥65 years and men ≥70 years should undergo BMD screening 1
• Postmenopausal women <65 years and men 50-70 years with one or more major risk factors (prior fracture, family history of fracture, glucocorticoid use ≥3 months at ≥5 mg prednisone equivalent daily) 1
• Premenopausal women and men 20-50 years with risk factors including chronic renal failure, rheumatoid arthritis, eating disorders, organ transplantation, prolonged immobilization, endocrine disorders (hyperparathyroidism, hyperthyroidism, Cushing syndrome, hypogonadism), or medications affecting BMD 1
• All adults initiating or continuing glucocorticoid therapy ≥2.5 mg/day for >3 months require initial clinical fracture risk assessment including BMD with vertebral fracture assessment (VFA) or spine x-rays within 6 months of therapy initiation 1

Additional Assessment for High-Risk Patients

For patients with T-scores <-1.0, DXA vertebral fracture assessment (VFA) is strongly recommended if any of the following are present: 1

• Women ≥70 years or men ≥80 years
• Historical height loss >4 cm (>1.5 inches)
• Self-reported but undocumented prior vertebral fracture
• Glucocorticoid therapy equivalent to ≥5 mg prednisone daily for ≥3 months

This is critical because 50-60% of patients with vertebral fractures detected on VFA have BMD in the non-osteoporotic range and were previously unaware of these fractures, which would reclassify them for treatment. 1

Follow-Up BMD Testing Intervals

For Patients NOT on Treatment

For patients with normal BMD (T-score ≥-1) and no major risk factors, repeat BMD testing is not routinely needed unless new risk factors develop. 2, 3

For patients with osteopenia (T-score between -1 and -2.5): 2

• T-score >-2.0 without risk factors: No routine follow-up needed unless new risk factors develop
• T-score ≤-2.0: Repeat BMD at approximately 2-year intervals

For patients on glucocorticoid therapy or at high risk for rapid bone loss: 1-year follow-up intervals are recommended after initiation or change of therapy 1, 2

For Patients ON Treatment

Patients receiving osteoporosis treatment should have BMD monitoring every 1-2 years during therapy. 1, 2

Important caveat: Scan intervals <1 year are discouraged because bone density changes occur slowly and may not exceed the least significant change of the DXA machine. 1, 2 Patients must be scanned on the same DXA machine, and BMD values (not T-scores) should be compared between scans. 1, 2

Special Population: Cancer Survivors

For childhood, adolescent, and young adult (CAYA) cancer survivors at risk (those treated with cranial/spinal radiation, total body irradiation, or corticosteroids): 1

• Initial BMD surveillance at entry into long-term follow-up (2-5 years after completing therapy)
• If normal (Z-score >-1), repeat at age 25 years when peak bone mass is achieved
• Between these timepoints and thereafter, perform BMD surveillance as clinically indicated based on BMD results and ongoing risk assessment

Management Based on BMD Results

For Adults ≥40 Years

Very High Fracture Risk (prior osteoporotic fracture OR T-score ≤-3.5 OR FRAX 10-year risk ≥30% for major osteoporotic fracture or ≥4.5% for hip OR glucocorticoid ≥30 mg/day for >30 days): 1

• Anabolic agents (PTH/PTHrP) are conditionally recommended over antiresorptive agents (bisphosphonates or denosumab)

High Fracture Risk (T-score ≤-2.5 but >-3.5 OR FRAX 10-year risk ≥20% but <30% for major osteoporotic fracture or ≥3% but <4.5% for hip): 1

• Denosumab or PTH/PTHrP are conditionally recommended over bisphosphonates

Moderate Fracture Risk (FRAX 10-year risk ≥10% and <20% for major osteoporotic fracture or >1% and <3% for hip OR T-score between -1 and -2.4): 1

• Oral or IV bisphosphonates, denosumab, and PTH/PTHrP are conditionally recommended

Critical warning: Sequential osteoporosis treatment is essential to prevent rebound bone loss and vertebral fractures after discontinuation of denosumab, romosozumab, and PTH/PTHrP. 1

For Adults <40 Years and CAYA Cancer Survivors

Z-score ≤-2: 1

• Refer to a medical bone health specialist (endocrinologist, internist, pediatrician, or rheumatologist depending on setting) for further endocrine evaluation, interpretation of BMD findings, treatment, and follow-up
• Important: Bisphosphonates are NOT recommended solely based on low BMD in the absence of fractures in this age group 1

Z-score ≤-1 and >-2: 1

• Evaluate for endocrine defects (hypogonadism, growth hormone deficiency)
• Consult bone health specialist as clinically indicated
• Repeat DXA after 2 years, then as clinically indicated based on BMD change exceeding the machine's least significant change and ongoing risk assessment

Patients with Fracture History

Any patient with a history of low-trauma vertebral or non-vertebral fractures should be referred to a bone health specialist for further evaluation and treatment, regardless of BMD. 1 Prior fracture is the strongest predictor of future fracture and increases relative risk approximately 2-fold or more. 4

Universal Lifestyle Recommendations

All at-risk patients, regardless of BMD Z-score or T-score, should receive counseling on: 1, 5

• Physical activity: Engage in regular weight-bearing exercise and fall prevention activities (150 minutes of moderate-intensity activity per week for adults; 60 minutes of moderate-to-vigorous activity daily for adolescents)
• Smoking cessation: Abstain from smoking completely
• Alcohol limitation: Limit or avoid alcohol intake
• Calcium intake: Consume at least 500-1000 mg/day of dietary calcium 1, 5
• Vitamin D: Consume at least 400-1000 IU/day; supplement if 25OHD levels <20 ng/ml 1, 5
• Nutritional support: Advise nutritional supplementation for patients with low BMI or underweight status

Patients at increased risk for vitamin D insufficiency (age >70 years, nursing home bound, chronically ill, or with gastrointestinal malabsorption) should take additional vitamin D supplementation. 5

Common Pitfalls to Avoid

• Do not rely solely on BMD without considering clinical risk factors - approximately half of people who develop osteoporotic fractures have BMD in the non-osteoporotic range 6
• Do not use QCT for routine surveillance - it is not recommended for BMD surveillance despite good precision 1
• Do not discontinue denosumab without transitioning to bisphosphonate therapy - this leads to increased risk of vertebral fractures 6
• Do not overlook men - they account for 24% of hip fractures and 21% of wrist fractures but receive only 10% of BMD tests and half the treatment rate of women 4
• Do not forget to assess for secondary causes of osteoporosis when patients fail to respond to therapy or experience incident fractures on treatment 7