Week 4 - Osteoporosis

Question 1

What is osteoporosis?

Answer 1

A systemic skeletal disease with low bone mass & architectural deterioration of bone tissue WITH a consequent increase in bone fragility and susceptibility to fracture.

Question 2

What are the main constituents of bone?

Answer 2

• Matrix (90%collagen; 10%proteins)
• Mineral (hydroxyapatite)
• Cells (osteo-blasts, -cytes, & -clasts)

Question 3

What are the functions of cortical bone?

Answer 3

• protection from trauma
• attachment of tendons & ligaments
• provides biomechanical strength

Question 4

What are the functions of trabecular bone?

Answer 4

• mineral metabolism

- strength & elasticity

Question 5

Which part of bone is most rapidly mobilized when body needs Calcium/phosphate?

Answer 5

Trabecular bone

Question 6

Where does PTH act & what does it do?

Answer 6

Bone - Ca & PO4 resorption
Kidney - Ca resorption; PO4 secretion

• also increases Calcitriol which acts on the intestine

Question 7

Where does Calcitriol act & what does it do?

Answer 7

Bone - Ca & PO4 resorption
Kidney - Ca & PO4 reabsorption
Intestines - Ca & PO4 absorption

Question 8

What are the determinants of healthy bone?

Answer 8

Structure/Mechanical - (fracture, BMD, architecture, biopsy)
Cell Function - (bone turnover)
Clinical risk factors/bone quality - (FRAX, CAROC, previous fall)

Question 9

What contributes to low bone mass?

Answer 9

• Low PBM (peak bone mass)
• Age-related bone loss
• Post-menopausal bone loss

Question 10

What are some risks for getting fractures?

Answer 10

• Low bone mass
• Clinical risk factors for falling
• Poor bone quality/architecture
• high BMI
• parental hx of fractures
• smoker
• any long-term use of glucocorticoids
• RA
• alcohol (3+ drinks/day)

Question 11

Briefly explain fracture epidemiology.

Answer 11

Peak in adolescence: males»females (usually trauma)

Rise with older age: females»males (rises after female age 40; male age 70)

Question 12

What are some types of vertebral fractures?

Answer 12

• wedge
• crush
• endplate

Question 13

How is bone mass/density assessed?

Answer 13

Plain films, DXA, CT, US

Question 14

What is the numerical cut point for a WHO dx of osteoporisis?

Answer 14

T score <= -2.5

Question 15

What is osteopenia?

Answer 15

Loss of bone mass with T-score between -1 and -2.5

Question 16

What is severe osteoporosis?

Answer 16

Osteoporosis (T<= -2.5) with fracture

Question 17

What is the difference between a T-score and a Z-score for fracture risk?

Answer 17

T-score is related to peak bone mass;

Z-score is an age-matched score for declining normal bone mass or developing bone

Question 18

What is the mechanism of Teriparatide?

Answer 18

• recombinant form of PTH
• anabolic agent (builds bone)
• INTERMITTENT USE stimulates more than osteoclasts

Question 19

What tool has the WHO made for assessing fracture risk?

Answer 19

FRAX

Question 20

Who is teriparatide given to?

Answer 20

Post-menopausal women with high risk of fracture.

Men or women who failed to respond to previous osteoporosis therapy.

Question 21

What is the function of giving PTH as one dose/day?

Answer 21

Increases bone-forming potential

Question 22

What is the classification criteria for severe osteoporosis?

Answer 22

T-score < -2.5 & previous fracture

Question 23

What accounts for the larger peak bone mass in males compared to women?

Answer 23

Androgens

Question 24

Compare incidence and mortality for fractures in men and women.

Answer 24

Men have lower incidence of fractures but higher mortality. Because fractures in women are more often due to osteoporosis but fractures in males usually happen if they are very sick already.

Question 25

Which two drugs both increase BMD and prevent fractures?

Answer 25

Alendronate & Teriparatide (does not affect hip fractures)

Question 26

What is the direct effect of glucocorticoids on osteoblasts?

Answer 26

• decreases proliferation/differentiation
• decreases osteocalcin
• decreases osteoprotegerin
• increases apoptosis

Question 27

What is the direct effect of glucocorticoids on osteocytes?

Answer 27

• causes apoptosis (thus decreases repair of microdamaged bone).

Question 28

What is the effect of glucocorticoids on osteoclasts?

Answer 28

• indirect effect via osteoblasts increasing RANKL & M-CSF expression to:
• Increase osteoclast recruitment
• Increase osteoclast differentiation
  (bone resorption)

Question 29

How does glucocorticoid use relate to Ca++?

Answer 29

Glucocorticoids decrease the action of Vit D and therefore reduce the absorption of Ca++

Question 30

What drug should be used to prevent/treat osteoporosis due to corticosteroid use?

Answer 30

Bisphosphenate

Question 31

What is the most common form of secondary osteoporosis?

Answer 31

Glucocorticoid-induced osteoporosis

Question 32

What type of bone does glucocorticoid-induced osteoporosis preferentially affect?

Answer 32

trabecular bone (early on)
proximal femur (later on)

Question 33

What is the second most common bone disease after osteoporosis?

Answer 33

Paget’s disease (Osteitis Deformans)

Question 34

What is Paget’s disease?

Answer 34

Rapid bone turnover
 - increased number & size of osteoclasts
 - overactive osteoblasts
Get disorganized matrix
Larger bone size
Brittle bone (deformed)

Question 35

What is the pharmacological treatment of Paget’s disease?

Answer 35

Bisphosphenates

Question 36

What is radiculopathy?

Answer 36

A neuropathy of the nerve root (ie. one of the nerves does not work properly).
Usually due to compression of the spine.
May cause pain, weakness, or numbness.

Question 37

How should bisphosphenates be taken?

Answer 37

Should be taken 1-2 hours before food, first thing in the morning, and should remain upright after taking it.

Question 38

What are some co-morbidities of falls?

Answer 38

• inflammatory arthritis
• celiac disease
• Type 2 DM
• IBD
• COPD