Osteoporosis

Question 1

What is OSTA and how is it calculated?

Answer 1

OSTA (Osteoporosis Self-assessment Tool for Asians) = Age - Weight

Low risk (< 0): Consider deferring DXA
Moderate risk (0-20): Consider DXA scan if any other risk factor present
High risk (>20): Consider DXA scan as chance of low BMD is high

Question 2

What are risk factors for osteoporosis?

Answer 2

• Post-menopausal women
• Men > 65yo
• Lack of exercise
• Smoking
• Excessive alcohol intake (>2 units/day)
• Family history of osteoporosis/fragility fracture
• Previous fragility fractures
• Low body weight
• Height loss (>2cm within 3 years)
• Low calcium intake (<500 mg/day)
• History of falls
• Prolonged immobility
• Medications (e.g. >5mg/day for >3 months of Prednisolone)

Question 3

When to treat osteoporosis?

Answer 3

• Patients presenting with fragility fracture OR
• Patients without fragility fracture but DXA T-score ≤ 2.5 OR
• Osteopenic (DXA T-score > -2.5 but < -1), but with high risk of fracture (FRAX >3% for hip, FRAX >20% for major osteoporotic)

Question 4

Alendronate MOA, Dose, Contraindications, SE

Answer 4

MOA: Inhibit osteoclast activity; promote apoptosis

Dose: 70mg q weekly (treatment), 35mg q weekly (prevention)

Contraindications:
Hypocalcemia, CrCl < 35ml/min, Unable to sit/stand for 30mins, increased risk of aspiration, Abnormalities of esophagus/conditions delaying gastric emptying

SE: Atypical femoral fractures, ONJ
GI irritation, dyspepsia, MSK pain, headache

Question 5

Risedronate MOA, Dose, Contraindications, SE

Answer 5

MOA: Inhibit osteoclast activity; promote apoptosis

Dose: 35mg q weekly (treatment and prevention)

Contraindications:
Hypocalcemia, CrCl < 30ml/min, Unable to sit/stand for 30mins, increased risk of aspiration, Abnormalities of esophagus/conditions delaying gastric emptying

SE: Atypical femoral fractures, ONJ
GI irritation, dyspepsia, MSK pain, headache

Question 6

Denosumab MOA, Dose, Contraindications, SE

Answer 6

MOA: Prevents RANKL from binding to receptors, reduce differentiation of precursor cells into osteoclast

Dose: SC 60mg q 6 months

CI: Hypocalcemia

SE: Similar to bisphosphonates (ONJ, AFF)

Ensure adequate Ca intake during treatment

Question 7

Raloxifene MOA, Dose, Contraindications, SE

Answer 7

MOA: Reduce bone resorption by acting as estrogen agonist in bone; estrogen antagonist in uterine and breast tissue

Dose: PO 60mg OD

CI: CrCl < 50ml/min, History of/current VTE, Hepatic and severe renal impairment, HyperTG (>5.6mmol/L)

SE: Hot flushes, leg cramp, peripheral oedema, arthralgia, flu-like sx
VTE (esp first 4 months)
Caution for non-ambulatory pts, stop for 3 days in undergoing elective surgery and resume when fully ambulatory

Question 8

Teriparatide MOA, Dose, Contraindications, SE

Answer 8

MOA: Recombinant PTH increase bone formation by stimulating osteoblast function and increase gastric and renal tubular absorption of calcium

Dose: SC 20 mcg OD

CI: Hypercalcemia, Paget’s disease, Hx of bone radiation

SE: Orthostatic hypotension, leg cramps, hypercalcemia

Treatment duration < 2 years

Question 9

Recommended calcium intake for osteoporosis?

Answer 9

1000-1200mg/day elemental calcium for healthy adults >51yo

800-1000mg/day elemental calcium for adults 19-50yo

[Should not exceed 1500mg/day]

Question 10

Elemental calcium content in calcium salts?
(Acetate, Carbonate, Chloride, Citrate, Gluconate, Lactate)

Answer 10

Acetate: 25%
Carbonate: 40%
Chloride: 27%
Citrate: 21%
Gluconate: 9%
Lactate: 13%

Question 11

Non-pharmacological measures for osteoporosis?

Answer 11

• Weight-bearing exercises (walking, Taichi, Stair climbing) & resistance exercises
• Avoid smoking
• Avoid alcohol consumption (≤ 2 units/day)
• Fall risk reduction (education, home mod, etc.)
• Calcium and Vit D intake (calcium foods such as milk, yogurt, cheese, tofu, almonds, dark leafy greens, beans)