At what Z scores should osteoporosis medications be initiated?

Osteoporosis Treatment Initiation Based on Z-Scores

Osteoporosis medications should be initiated at a Z-score of -2.5 or less in adults 40 years and older, and at a Z-score of -3.0 or less in adults under 40 years of age. For patients on glucocorticoids, treatment should be initiated at higher Z-scores (-2.0 or less).

Treatment Thresholds by Age Group

Adults ≥40 Years:

• Primary threshold: T-score of -2.5 or less at hip or spine 1
• Additional criteria warranting treatment:
  • History of fragility fracture 1, 2
  • FRAX 10-year risk of major osteoporotic fracture ≥10% 1
  • FRAX 10-year risk of hip fracture >1% 1

Adults <40 Years:

• Primary threshold: Z-score of -3.0 or less at hip or spine 1
• Additional criteria warranting treatment:
  • History of osteoporotic fracture 1
  • Bone loss ≥10%/year at hip or spine (especially with prednisone >7.5 mg/day) 1

Special Populations

Glucocorticoid Users:

• Treatment recommended at higher Z-scores (≤-2.0) 1
• Consider treatment for all patients on prednisone ≥7.5 mg/day for ≥6 months 1
• Very high-dose glucocorticoid users (≥30 mg/day) should be considered for treatment regardless of Z-score 1

Women of Childbearing Potential:

• Oral bisphosphonates are first-line if not planning pregnancy 1
• Teriparatide is second-line option 1
• Ensure effective contraception during treatment 1

Cancer Patients:

• For breast cancer patients on aromatase inhibitors: treatment if T-score ≤-2.5 1
• For patients with bone metastases: intravenous bisphosphonates recommended 1

Treatment Algorithm

1. Assess fracture risk:

   • Measure BMD via DEXA scan
   • Calculate FRAX score (with glucocorticoid adjustment if applicable)
   • Evaluate clinical risk factors

2. Determine treatment threshold:

   • Age ≥40: T-score ≤-2.5 or FRAX criteria met
   • Age <40: Z-score ≤-3.0 or specific risk factors present
   • Glucocorticoid users: Z-score ≤-2.0 or specific risk factors

3. Select appropriate medication:

   • First-line: Oral bisphosphonates 1, 3
   • Second-line options (if oral bisphosphonates inappropriate):
     • IV bisphosphonates
     • Teriparatide
     • Denosumab
     • Raloxifene (postmenopausal women only)

Important Considerations

• Calcium and vitamin D: Ensure adequate intake (1,000-1,200 mg calcium and 600-800 IU vitamin D daily) 1, 3
• Vitamin D levels: Target serum level ≥20 ng/mL 1, 3
• Lifestyle modifications: Weight-bearing exercise, smoking cessation, limiting alcohol to 1-2 drinks/day 1
• Monitoring: Repeat BMD testing every 2-3 years depending on risk factors 1

Common Pitfalls to Avoid

1. Failing to correct vitamin D deficiency before starting bisphosphonates, which may reduce their efficacy 1, 3
2. Not considering drug holidays after 5 years of oral bisphosphonate or 3 years of IV bisphosphonate therapy in lower-risk patients 4
3. Overlooking the need for dental work before initiating bisphosphonate therapy to reduce risk of osteonecrosis of the jaw 1, 3
4. Ignoring rebound bone loss when discontinuing denosumab without transitioning to another antiresorptive agent 3
5. Using T-scores instead of Z-scores when evaluating premenopausal women or men under 50 years 1

By following these evidence-based guidelines, clinicians can appropriately identify patients who would benefit from osteoporosis treatment, potentially reducing fracture risk and associated morbidity and mortality.