Bone Health

Question 1

How is osteoporosis characterised?

Answer 1

A progressive skeletal systemic disease:

• Low bone mass
• Micro architectural deterioration of bone tissue
• Result in bone fragility and increased susceptibility to fracture

Question 2

How is osteoporosis defined?

Answer 2

A BMD of 2.5 standard deviations (T=2.5) or less when compared to that of healthy young adults of the same sex.

Question 3

What are risk factors for osteoporosis?

Answer 3

• Post menopausal women
• Low BMI elderly
• Smokers
• Use of corticosteroids
• Rheumatoid arthritis
• Diabetes
• FH of hip fractures

Question 4

What are the 2 primary functions of bone remodelling?

Answer 4

1. Repair micro damage within skeleton to maintain strength

2. Supply calcium from the skeleton to maintain serum calcium

Question 5

What are the hormone levels in primary hyperparathyroidism?

Answer 5

Calcium - high
PTH - high
Phosphate - low

Question 6

What are the hormone levels in secondary hyperparathyroidism?

Answer 6

Calcium - low/normal
PTH - high
Phosphate - high/normal

Question 7

What are the hormone levels in tertiary hyperparathyroidism?

Answer 7

Calcium - high
PTH - really high
Phosphate - high

Question 8

How do you identify at risk patients?

Answer 8

• Calculate FRAX score
• Routine bloods including TFTs, calcium, vit D (PTH + myeloma screen if indicated)
• Refer to NOGG based on FRAX - lifestyle advice + reassure, BMD or treatment

Question 9

How do you measure BMD?

Answer 9

DEXA scan
A defined wavelength of energy is passed through the area and through complex mathematical equations give us the density:
- Measures the mineral content of bone
- Low energy radiation
- Shorter scan times
- Accurate
- Focus on trabecular bone which has high metabolic activity and bone loss quickest

Question 10

Why is BMD low sensitivity?

Answer 10

Fragility fractures will occur in women who do not have osteoporosis as defined by a T score

Question 11

Other than BMD how else is osteoporosis diagnosed?

Answer 11

• Spine/hip# in the absence of major trauma

- Fractures of other sites (pelvis, humerus, wrist) + presence of low BMD

Question 12

What markers are used for fracture risk?

Answer 12

CTX - bone resorption
P1NP - bone formation
- Predict fracture risk independent of BMD
- Predict fracture risk reduction when starting Rx
- Provide a marker for assessing compliance
- Use to decide on a drug holiday

Question 13

What are non-pharmacological measures of osteoporosis?

Answer 13

Stop smoking

Exercise

Question 14

What needs to be replaced before pharmacological therapy in osteoporosis?

Answer 14

If Vit D level low, load with cholecalciferol 40,000 units once a week for 7 weeks before starting Adcal D3.
VitD needs to be replaced before bisphosphonates are started.

Question 15

What is the 1st line treatment in osteoporosis?

Answer 15

Bisphosphonates regulate osteoclast function - advise 3-5yrs treatment

• Alendronate is 1st line, all patients need regular vitD
• Rare SEs: osteonecrosis of jaw, atypical fractures of femur
• 2nd line: zolendronic acid and denosumab

Question 16

What is mechanism of denosumab?

Answer 16

• Twice yearly by SC administration
• Increase BMD in the spine, hip and forearm
• Binds to RANKL, inhibiting osteoclast maturation, reducing osteoclast survival

Question 17

What is denosumab approved for?

Answer 17

• High risk of osteoporotic fractures
• Failed or intolerant to other osteoporosis therapy
• Men at high risk, men with prostate cancer on GnRH agonist therapy
• Women with breast cancer on aromatise inhibitor therapy
• Patients with a creatinine clearance <35 >20

Question 18

What is the dosage of PTH (teriparatide)?

Answer 18

Used if sustained minimum 3 fractures + T < 3.5
Daily SC injection given for max 2yrs
Reduced:
- Vertebral fractures by 65%, non-vertebral by 45%
Mono therapy, followed by antiresorptive agent
SEs: leg cramps, muscle pain, weakness, dizziness, headache and nausea

Question 19

How do you assess if the patient should stop bisphosphonates?

Answer 19

People at increased risk of fractures should continue, this includes:

• Previous hip or vertebral fracture
• 1 or more low trauma fractures during treatment
• On current oral glucocorticoids of 7.5mg or more prednisolone/day or equivalent
• Age >75yrs
• T score on DEXA scan

Question 20

How do you interpret DEXA scan scores?

Answer 20

• Above -1 SD is normal
• -1 to -2.5 is mildly reduced BMD
• < -2.5 is osteoporotic
• > -2.5 can have a treatment holiday with reassessment of fracture risk and BMD after 2 years.