Osteoporosis

Question 1

15 Risk Factors for Low Bone Mass

Answer 1

female
post-menopause
family hx, fracture
Caucasian then Asian
thin/frail
low dietary Ca or low Vit D
alcohol
smoking
lack of wt bearing exercise
hyperthyroidism
hyperparathyroidism 
glucocorticoids
excess thyroid replacement
anti-convulsants
many other meds

Question 2

Who should be screened for osteoporosis?

Answer 2

• Women > 65 yo
• Post-menopausal women, <65 yo w/ known risk factor
• Men > 70 yo

Question 3

Osteoporosis Dx

Answer 3

• DXA (dual X-ray absorptiometry)
  
  • Low radiation, 5 min long
  • Meas bone mass then use T score
    
    • Normal … 1 or more SD
    • Osteopenia … < 1-2.5 SD
    • Osteoporosis … < 2.5 SD
• Can also use spine imaging (lateral thoracic and lumbar X-rays)
  
  • Do if low bone mass + kyphosis or dec height
  • Vertebral fractures below T6, those that show anterior wedging and involvement of more than 1 vertebrae are consistent with osteoporosis

Question 4

What is included in a fracture prevention regimen?

Answer 4

• Ca (Ca citrate or Ca carbonate) + Vit D + wt bearing exercise (no swimming) + smoking cessation
• Fall prevention - (esp in elderly) physical therapy, occupational therapy, medication adjustments to limit or avoid long-acting benzodiazepines and antipsychotics

Question 5

3 Indications for Osteo Tx

Answer 5

• DXA T-score ≤ -2.5 spine, femoral neck, total hip after secondary evaluation (osteoporosis category)
• Adult fragility fracture of the hip or spine (fragility fracture = from standing ht or less)
• DXA T-score between -1 and -2.5 (osteopenia category) PLUS 10 year probability hip fracture ≥ 3% by FRAX® or 10 year probability any major osteoporotic fracture ≥ 20% using FRAX
  - FRAX = assessment tool for prognosis

Question 6

Bisphosphonates (MAO and side effects)

Answer 6

• MAO: block pathway to production of cytoskeleton by osteoclast; stabilize by dec bone turnover but do not inc osteoblast activity
• Side effects: GI if oral (GERD, esophagitis, ulcers, gastritis), rarely osteonecrosis of jaw, atypical fracture (cannot repair small stress fractures –> prodromal pain in lateral femur –> clean transverse break)
• Remain in bone for yrs even after stopped; consider break from drug after 5 yrs oral or 3 yrs IV

Question 7

Specific Oral v IV Bisphosphonates

Answer 7

• Oral Agents - must take first thing in morning w/ full glass water and remain upright (poorly absorbed)
  
  • Alendronate, risedronate
• IV - less frequent doses; can have flu-like acute phase reaction w/in 24-48 hrs infusion
  
  • Zoledronic acid (kidney clearance), ibandronate (vertebral fractures only)

Question 8

Denosumab

Answer 8

• MAO: IgG2 antibody that binds RANK ligand receptor on osteoclast
• Side Effects: rare skin infections and hypocalcemia
• Sub Q injection

Question 9

Teriparatide

Answer 9

• MAO: ANABOLIC; only drug that builds up bone; active 34 amino acids of parathyroid hormone (PTH 1-34)
• Daily subcutaneous injection (only use for 2 yrs then transition to bisphosphonates)