Osteoporosis & Metabolic Bone Disease: Mini Symposium Flashcards
What is the definition of osteoporosis?
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
What is the epidemiology of fractures in older men and women?
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
What is the most important factor to consider in an osteoporotic patient?
Fracture risk (this is what is treated in an osteoporosis patient)
What investigations are performed to diagnose osteoporosis?
- DXA bone scan (dual-energy x-ray absorptiometry)
What type of drugs are used to prevent osteoporosis?
Prevent Osteoporosis:
- HRT
- SERMS
How is Vitamin D and Calcium metabolised in the body?
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:
What is the pathogenesis of osteomalacia?
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
What is Osteomalacia?
Adult equivalent of Ricket’s, i.e. insufficient bone mineralisation caused by a severe nutritional Vitamin D insufficiency
What investigations are performed to diagnose osteomalacia and what results would be expected?
Blood tests:
- Reduced calcium and phosphate
- Increased alkaline phosphate
- Increased PTH
X-ray:
- Loss of cortical bone
What are the clinical features of Osteomalacia and Rickets?
Rickets:
- Failure to thrive
- Bone deformity
- Wide bones
Osteomalacia:
- Bone fractures
- Bone pain
- Gait disturbances
How can Osteomalacia be differentiated from other metabolic bone diseases such as Paget’s disease?
Blood tests:
- Osteomalacia will show reduced serum Calcium and Vitamin D3
- Pagets will show normal serum Calcium
What are the principles of prevention and treatment of osteomalacia?
Treatment:
- Vitamin D and Calcium supplements
What is Paget’s disease?
- 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
What is the epidemiology of Paget’s disease?
- Strong genetic component
- 15-30% of cases are familial
- Restricted to those of Anglo-Saxon origins
What is the aetiology of Paget’s disease?
- Increased bone resorption
- Increased bone formation
What are the clinical features of Paget’s disease?
- Bone pain and local heat
- Bone deformity or fracture
- Hearing loss
What investigations are performed to confirm the diagnosis of Paget’s disease?
- Isotope bone scan
What are the principles of management of Paget’s disease?
- 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
Which drugs are used to treat osteoporosis?
- Bisphosphonates (1st choice)
- Denosumab
- Teriparatide
Are men or woman more likely to suffer from osteoporosis?
Woman
How is a diagnosis of osteoporosis made?
DXA scan T score of < -2.5 SD’s below mean of a 30-40 year old woman = Osteoporosis
Once the biologically active form of Vitamin D has been formed by the kidney, what are its functions?
1 - Promotes absorption of calcium from the gut
2 - Stimulates bone remodelling of the skeleton
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)?
Parathyroid hormone levels increase in order to increase serum calcium levels (lack of vitamin D causes a reduction in calcium absoprtion from the gut)
By which mechanisms does parathyroid hormone increase serum calcium levels?
1 - Increasing bone resorption
2 - Reducing renal calcium excretion
3 - Stimulating production of 1,25(OH)2D - the active form of Vitamin D
