Osteoporosis & Metabolic Bone Disease: Mini Symposium

Question 1

What is the definition of osteoporosis?

Answer 1

A metabolic bone disease characterised by low bone mass and micro architectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk

Question 2

What is the epidemiology of fractures in older men and women?

Answer 2

Female > 50: 1 in 2 will have an osteoporotic fracture before they die

Male > 50: 1 in 5 will have an osteoporotic fracture before they die

• A 50 year old woman has a lifetime risk of 17% of a hip fracture

Question 3

What is the most important factor to consider in an osteoporotic patient?

Answer 3

Fracture risk (this is what is treated in an osteoporosis patient)

Question 4

What investigations are performed to diagnose osteoporosis?

Answer 4

• DXA bone scan (dual-energy x-ray absorptiometry)

Question 5

What type of drugs are used to prevent osteoporosis?

Answer 5

Prevent Osteoporosis:

• HRT
• SERMS

Question 6

How is Vitamin D and Calcium metabolised in the body?

Answer 6

Vitamin D:

1 - Sunlight on the skin releases 7DHC

2 - The Liver converts 7DHC into 25(OH)Vit D

3 - Finally the Kidney produces 1, 25 (OH)2 Vit D

Calcium:

Question 7

What is the pathogenesis of osteomalacia?

Answer 7

1 - Severe nutritional Vitamin D deficiency

2 - Lack of calcium and phosphate absorption from the gut

3 - As a result of poor calcium and phosphate absorption, there is insufficient mineralisation of bones resulting in osteomalacia

Question 8

What is Osteomalacia?

Answer 8

Adult equivalent of Ricket’s, i.e. insufficient bone mineralisation caused by a severe nutritional Vitamin D insufficiency

Question 9

What investigations are performed to diagnose osteomalacia and what results would be expected?

Answer 9

Blood tests:

• Reduced calcium and phosphate
• Increased alkaline phosphate
• Increased PTH

X-ray:

• Loss of cortical bone

Question 10

What are the clinical features of Osteomalacia and Rickets?

Answer 10

Rickets:

• Failure to thrive
• Bone deformity
• Wide bones

Osteomalacia:

• Bone fractures
• Bone pain
• Gait disturbances

Question 11

How can Osteomalacia be differentiated from other metabolic bone diseases such as Paget’s disease?

Answer 11

Blood tests:

• Osteomalacia will show reduced serum Calcium and Vitamin D3
• Pagets will show normal serum Calcium

Question 12

What are the principles of prevention and treatment of osteomalacia?

Answer 12

Treatment:

• Vitamin D and Calcium supplements

Question 13

What is Paget’s disease?

Answer 13

• A localised disorder of bone turnover
• Increased bone resorption followed by increased bone formation
• This leads to disorganised bone: bigger, less compact, more vascular and more susceptible to deformity and fracture

Question 14

What is the epidemiology of Paget’s disease?

Answer 14

• Strong genetic component
• 15-30% of cases are familial
• Restricted to those of Anglo-Saxon origins

Question 15

What is the aetiology of Paget’s disease?

Answer 15

• Increased bone resorption
• Increased bone formation

Question 16

What are the clinical features of Paget’s disease?

Answer 16

• Bone pain and local heat
• Bone deformity or fracture
• Hearing loss

Question 17

What investigations are performed to confirm the diagnosis of Paget’s disease?

Answer 17

• Isotope bone scan

Question 18

What are the principles of management of Paget’s disease?

Answer 18

• Paget’s only treated in symptomatic cases (unless Paget’s is present in skull, or an area requiring surgical intervention)
• Paget’s treated using IV Bisphosphonates

Question 19

Which drugs are used to treat osteoporosis?

Answer 19

• Bisphosphonates (1st choice)
• Denosumab
• Teriparatide

Question 20

Are men or woman more likely to suffer from osteoporosis?

Answer 20

Woman

Question 21

How is a diagnosis of osteoporosis made?

Answer 21

DXA scan T score of < -2.5 SD’s below mean of a 30-40 year old woman = Osteoporosis

Question 22

Once the biologically active form of Vitamin D has been formed by the kidney, what are its functions?

Answer 22

1 - Promotes absorption of calcium from the gut

2 - Stimulates bone remodelling of the skeleton

Question 23

What happens to parathyroid hormone levels when there is a lack of Vitamin D being absorbed by the body (either through dietary deficiency or lack of sunlight)?

Answer 23

Parathyroid hormone levels increase in order to increase serum calcium levels (lack of vitamin D causes a reduction in calcium absoprtion from the gut)

Question 24

By which mechanisms does parathyroid hormone increase serum calcium levels?

Answer 24

1 - Increasing bone resorption

2 - Reducing renal calcium excretion

3 - Stimulating production of 1,25(OH)2D - the active form of Vitamin D

Question 25

Although PTH can help restore serum calcium levels back to normal in the short term, what are the long term consequences of elevated PTH levels due to reduced Vitamin D?

Answer 25

1 - Hypocalcaemia (due to depleted 25(OH)D levels)

2 - Osteomalacia & Rickets

Question 26

What are the differences between the presenting features of osteomalacia and Pagets disease?

Answer 26

Pagets disease pain = deep, boring pain

Also, the blood results in the Pagets will show normal Calcium and Phsophate

Question 27

What gene is thought to be defective in Pagets?

Answer 27

SQSTM1

Question 28

What would the blood results for Pagets disease?

Answer 28

• Significant elevation of Serum Alkaline Phosphotase
• Normal Calcium and Phosphate