OSTEOPEROSIS

Question 1

What is the difference between the definitions of osteopenia and osteoporosis?

Answer 1

Osteopenia is a decrease in bone mass; osteoporosis is a markedly decreased bone mass such that fracture risk goes up

Question 2

What part of the bone does osteoporosis affect the most?

Answer 2

Trabecular bone > cortical bone

Question 3

In what parts of the skeleton is the high trabecular bone content? 3 listed

Answer 3

• Spine
• Head of femur
• Wrist (distal radius)

Question 4

Why are elderly white females more likely to develop osteoporosis?

Answer 4

Men reach a higher peak bone mass than women. Bone mass decreases slowly after the age of 30 to 40, and loss is accelerated after menopause. Whites lose more mass than blacks.

Question 5

What action does oestrogen normally have on bone?

Answer 5

Suppression of osteoclast activity

Question 6

What are calcium, PTH, ALP levels in osteoporosis?

Answer 6

Normal - high yield

Question 7

What produces RANK ligand? Where is its receptor? What is its function?

Answer 7

• Produced by osteoblasts
• RANK receptor is on osteoclasts
• Plays key role in osteoclast formation, function and survival

Question 8

What inhibits RANK ligand? What is the function of this? What produces this inhibitor?

Answer 8

Osteoprotegerin (OPG): regulates bone resorption

Osteoblasts (also produce RANK ligand)

Question 9

How do glucocorticoids cause osteoporosis on a molecular level?

Answer 9

• Suppress synthesis of OPG
• Increase production of RANK receptor on osteoclasts

END RESULT→ Increased bone resorption + reduced bone formation

Question 10

What are the two main lifestyle factors that can increase osteoporosis risk?

Answer 10

Smoking, alcohol

Question 11

Which antiepileptic drugs increase the risk of osteoporosis with long-term therapy? Explain why this happens

Answer 11

Phenobarbital, phenytoin, carbamazepine

• cytochrome P450 enzyme inducers
• increases breakdown of vitamin D → less calcium → increased PTH → bone loss

Question 12

Explain how to avoid iatrogenic hyperthyroidism. How would fracture risk be altered if this was not prevented?

Answer 12

Measuring TSH levels: if low this indicates a lower dose of levothyroxine is needed. Hyperthyroidism accelerates bone loss and increases risk of osteoporosis and fractures

Question 13

How can you diagnose osteoporosis? Two points

Answer 13

• Fragility fracture (fall from standing height or less causing fracture) or spontaneous compression fracture
• T score -2.5 or less

Question 14

Explain how a DEXA scan measures the T score. What does the T score mean?

Answer 14

Dual energy x-ray absorptiometry

• Two x-rays of different energy levels aimed at bones (spine and hip)
• T score is patient’s bone mineral density vs density of a healthy 30-year-old
• >-1.0 is normal

Question 15

Why are many elderly people short?

Answer 15

Shrinkage of spine over time from compression fractures, as well as kyphosis