Osteoporosis and metabolic bone diseases

Question 1

Learning outcomes

Answer 1

• Understand the physiological mechanisms underpinning calcium balance
• Know how osteoporosis is diagnosed, why it pre-disposes to fractures and how common it is
• List common secondary causes of osteoporosis
• Know how to estimate a patient’s risk of fracture
• List the main treatments for osteoporosis, their mechanisms of action and adverse effects
• Describe the main features of osteomalacia, rickets and Paget’s disease of bone
• Describe the common diseases that cause high blood calcium levels

Question 2

Daily calcium handling

Answer 2

Most calcium absorbed will be excreted- net absoprtion of 5/25 mmol pd
Will enter bloodstream (circulating calcium levels)
Calcium is mainly stored in bones (30000mmol)
Kidney filtration and reabsorption of calcium

Vit D picture in lecture, deoxycholestrol >cholecalciferol etc
Acts on gut to inc. calcium absorption
Bone increased calcification
Kidney increased resorption

Question 3

Bone turnover

Answer 3

Bones are very metabolically active tissue
-Metabolic signal or small damage to bone, osteoclasts switched on and dissolve bone
Osteoblasts form new bone (osteoid), calcified and turned into healthy bone

Question 4

Osteoporosis

Answer 4

A progressive systemic skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture
Normal blood tests
No symptoms

Question 5

Fragility fracture

Answer 5

Affect more than 1/3 women and 1/5 men

Over 50% of patients suffering a hip fracture can no longer live independently and over 25% die within 12 months

In the UK, >500,000 new fragility fractures / year

Annual cost to NHS at least £4.4 billion

After breaking a bone, around 80% of patients are not diagnosed and treated for osteoporosis¹

One in five women who have broken a bone will break three or more before being diagnosed with osteoporosis- DXA scan

Fracture liaison services aim to stop this

Question 6

Risk factors for osteoporosis

Answer 6

• Post-menopausal female
• Advancing age
• Early menopause
• Corticosteroid exposure
• Smoking
• Alcohol
• Genetic factors
• Low body weight
• Rheumatoid arthritis

Question 7

Treating osteoporosis- lifestyle

Answer 7

Smoking
Alcohol
Exercise
Calcium
Vitamin D
Protein
Falls risk