Diagnosing Early Osteoporosis
Initial Screening Approach
All women aged 65 years or older should undergo dual-energy x-ray absorptiometry (DEXA) screening regardless of risk factors, and postmenopausal women younger than 65 years should be screened if their 10-year fracture risk equals or exceeds that of a 65-year-old white woman without additional risk factors. 1, 2
Who Should Be Screened
- Women aged ≥65 years: Routine DEXA screening is recommended for all women in this age group 1, 2
- Men aged ≥70 years: Routine DEXA screening should be performed 1, 2
- Postmenopausal women <65 years: Screen if elevated fracture risk based on clinical assessment 1, 2
- Men <70 years: Screen only if significant risk factors present (previous fragility fracture, long-term glucocorticoid therapy ≥7.5 mg/day prednisone for ≥3 months, conditions causing secondary osteoporosis) 1, 2
High-Risk Groups Requiring Earlier Screening
Screen immediately regardless of age if any of the following apply:
- Previous fragility fracture (fracture from standing height or less) 2, 3
- Long-term glucocorticoid therapy (≥7.5 mg/day prednisone equivalent for ≥3 months) 1, 2
- Medical conditions causing bone loss: hyperparathyroidism, hyperthyroidism, hypogonadism, malabsorption syndromes, chronic inflammatory diseases 2, 4
- Medications associated with bone loss: aromatase inhibitors, androgen deprivation therapy, GnRH agonists 1, 2
- Chemotherapy-induced premature menopause 1
Diagnostic Testing
DEXA Scan Protocol
DEXA of the hip and lumbar spine is the gold standard for diagnosing osteoporosis. 1, 5
- Measure both sites: Obtain BMD at lumbar spine (L1-L4) and proximal femur (femoral neck and total hip) 1, 5
- Timing: Perform within 6 months of initiating long-term glucocorticoid treatment 1
- Interpretation:
Vertebral Fracture Assessment (VFA)
VFA or standard spine radiography should be performed if T-score <-1.0 and any of the following apply:
- Women aged ≥70 years or men aged ≥80 years 2
- Historical height loss >4 cm 2
- Self-reported but undocumented prior vertebral fracture 2
- Glucocorticoid therapy ≥5 mg prednisone daily for ≥3 months 2
Critical pitfall: Vertebral fractures are diagnostic of osteoporosis even if BMD is not in the osteoporotic range, and these fractures are the strongest predictor of future fractures 1, 4
Clinical Fracture Risk Assessment
FRAX Tool Application
Calculate 10-year fracture risk using FRAX (https://www.shef.ac.uk/FRAX/tool.jsp) for all adults ≥40 years being evaluated for osteoporosis. 1, 2
- Glucocorticoid dose adjustment: If prednisone dose >7.5 mg/day, increase major osteoporotic fracture risk by 15% and hip fracture risk by 20% 1
- Example: If calculated hip fracture risk is 2.0%, adjust to 2.4% for doses >7.5 mg/day 1
- Treatment threshold: Consider treatment if 10-year major osteoporotic fracture risk >10% 1
Risk Factors to Document
Obtain detailed history including:
- Glucocorticoid use: Dose, duration, pattern of use 1
- Falls assessment: Frequency, circumstances, environmental hazards 1
- Fracture history: Previous fragility fractures, vertebral compression fractures 1, 3
- Lifestyle factors: Smoking (current or past), alcohol use ≥3 units/day, inadequate calcium/vitamin D intake 1
- Family history: Hip fracture in first-degree relative 1
- Physical examination: Height measurement (compare to historical maximum), weight, kyphosis, spinal tenderness, muscle strength 1
Common pitfall: Height loss >4 cm or development of kyphosis suggests undiagnosed vertebral fractures and warrants immediate imaging 1, 2
Screening Intervals
For Normal or Mildly Low BMD
- Normal BMD (T-score ≥-1.0): Repeat DEXA in 4-8 years for women ≥65 years; transition to osteoporosis takes approximately 17 years 2
- Mild osteopenia (T-score -1.0 to -1.49): Repeat in 3-5 years 2
- Moderate osteopenia (T-score -1.5 to -1.99): Repeat in 2-3 years; transition to osteoporosis occurs in approximately 5 years 2
For High-Risk Patients
- Glucocorticoid therapy: Repeat DEXA every 1-2 years due to accelerated bone loss 2
- Aromatase inhibitor or androgen deprivation therapy: Repeat every 2 years 1, 2
- Established osteoporosis on treatment: Repeat every 1-2 years to monitor treatment effectiveness 2, 3
Critical pitfall: Do not repeat DEXA scans more frequently than every 2 years in stable patients, as testing precision limitations prevent reliable measurement of change over shorter intervals 2
Laboratory Evaluation
Obtain baseline laboratory tests to exclude secondary causes of osteoporosis:
- Complete blood count, comprehensive metabolic panel (calcium, phosphate, alkaline phosphatase, creatinine) 4
- 25-hydroxyvitamin D level 1, 4
- Thyroid-stimulating hormone 4
- Consider: serum protein electrophoresis (if elevated total protein), parathyroid hormone (if hypercalcemia), testosterone (in men), 24-hour urinary calcium (if history of kidney stones) 4
Special Populations
Glucocorticoid-Induced Osteoporosis
Patients on glucocorticoids develop osteoporosis at higher BMD levels than postmenopausal osteoporosis; therefore, treatment should be considered at T-score ≤-1.5 rather than -2.5. 1, 4
- Perform clinical fracture risk assessment within 6 months of starting long-term glucocorticoids 1
- Patients <40 years are at moderate risk if expected to continue ≥7.5 mg/day prednisone for ≥6 months AND have hip/spine Z-score <-3 OR rapid BMD decline ≥10% in 1 year 1
Men
Men have substantially higher mortality following osteoporotic fractures than women, with >33% dying within 1 year of hip fracture. 1