Flashcards in Disorders of bone health including osteoporosis Deck (68):
What is osteoporosis?
Progressive skeletal disease characterised by low bone mass and microarchitectual deterioration of bone structure
Which sex gets osteoporosis more commonly?
How does osteoporosis present?
Asymptomatic until fractures
Over which age is osteoporosis frequent?
What are the common osteoporotic fracture sites?
Neck of femur
What is the domino effect in relation to osteoporosis?
An increasing number of vertebral fractures due to osteoporosis causing progressive curvature of the spine
Where does bone remodelling occur?
Bone remodelling units
Describe bone remodelling
Osteoclasts begin to reabsorb bone at specific sites >
Osteoclasts replaced by osteoblasts which lay down osteoid >
Osteoid undergoes mineralisation to bone >
Resorptive cavity completely filled with new bone
How is bone remodelling altered in osteoporosis?
Reabsorption of bone occurs more than formation
How is osteoporotic bone architecture different from normal bone?
Large spaces and breaks
Which factors are important in bone density?
Which factors contribute to bone density loss?
Lowered sex hormones (menopause)
Low body weight
Calcium deficient diet
Disease affecting bones
Drugs (e.g steroids)
How does bone density change with age?
Bone density increases until around 30
After 40 it begins to decline slowly
During and after menopause bone density loss is rapid and oestrogen deficiency can further perpetuate this
What are the non-modifiable risk factors for fragility fractures?
Early menopause (
What are the modifiable risk factors for fragility fractures?
Bone mineral density
Which diseases increase the risk factor for an osteoporotic fragility fracture?
Chronic liver disease
Who should be risk assessed?
Patients over 50 with risk factors
Patients under 50 with serious risk factors (steroids, early menopause)
Who should be referred for a dexa bone scan?
High risk patients
How is bone mineral density measured?
DEXA bone scan
Is bone mineral density a dependent or independent risk factor for fragility fractures?
What is osteopenia?
Low bone density above 1 standard deviation below expected
What is osteoporosis?
Low bone density over 2 and a half standard deviations below expected
What is severe osteoporosis?
Low bone density over 2 and a half standard deviations below expected + fragility fracture
How can osteoporosis be classified in patients younger than 20?
Using the z score
As bone mineral density increases what happens to the risk of fracture?
How should suspected osteoporosis be investigated?
Protein electrophoresis/bence jones proteins (myeloma)
List some secondary causes of osteoporosis
Chronic liver disease
Chronic kidney disease
What lifestyle changes can be helpful in the management of osteoporosis (not diet)?
Risk assessment for falls and prevention
High intensity strength training
Low intensity weight bearing
Avoidance of alcohol excess
What diet changes can be helpful in the management of osteoporosis?
2-3 portions of milk/dairy per day (700g)
3-4 portions of milk/dairy per day (1000g) post menopausal
Non dairy sources (bread, fortified cereal, fish w/ bones, green veg, beans)
When are calcium and/or vitamin D supplements indicated?
Considered as risk reduction of non-vertebral fracture in patients at risk of deficiency due to diet or limited sunlight (housebound, cultural garb)
When should calcium not be taken?
Within two hours of oral biphosphonates
When would vitamin D alone be indicated?
When oral calcium intake is adequate
How do biphosphonates work?
Anti-resorptive agents - analogues of pyrophosphate that get absorbed onto bone and eaten by osteoclasts causing cell death and less reabsorption
Give two examples of biphosphonates
What do biphosphonates reduce the risk of?
Spine and hip fractures
When are biphosphonates indicated?
T score less than -2.5
Existing fragility fracture
How long should biphosphonates be given for?
5 yr +
10 yr + if vertebral fracture
What are the risks of long term biphosphonate use?
Osteonecrosis of the jaw
How is zoledronic acid given?
Once yearly IV infusion (5mg in 100ml NaCl) for 5 years
What is a common side effect of zoledronic acid and how can this be treated?
Influenza like symptoms (acute phase reaction)
How does denosumab work?
Human monoclonal antibody targeting RANKL - inhibiting activation, development of osteoclasts and decreased reabsorption so increased density
How is denosumab administered?
Subcutaneous injections 6 monthly
Which osteoporosis drug can be administered in severe renal failure?
What are the side effects of denosumab?
What is strontium ranelate?
When is strontium ranelate contraindicated?
Ischaemic heart disease
Peripheral artery disease
When is strontium ranelate indicated?
When there is no other option
What is teriparatide?
Recombinant parathyroid hormone
How does teriparatide work?
Stimulates bone growth
When is teriparatide indicated?
Over 65 with T score -3.5 plus 2 fragility fractures
55-64 with T score
When should patients be treated for osteoporosis?
Anti-resorptive therapy T score 7.5 for 3 months or more OR prevalent fracture and T score
What are the direct and indirect effects of corticosteroids on bone?
Direct - reduced osteoblast activity, suppression of osteoblast growth and reduction in calcium absorption
Indirect - reduced gonadal and adrenal hormones
Are the fracture risks of glucocorticoids dose dependent?
Yes but no safe dose
What is Paget's disease?
Abnormal osteoclast activity followed by increased osteoblast activity resulting in weakened bone and increased fracture risk
What is the term for paget's at a single site? What about at multiple sites?
What is the aetiology of Paget's?
Which bones does Paget's affect?
Which age group is affected by Paget's?
How does Paget's disease present?
What is a rare complication of Paget's?
How can Paget's be investigated?
Isotope bone scan
Isolated raise on alkaline phosphate
How is Paget's treated?
Analgesia +/- biphosphonates if not responding
What is osteogenesis imperfecta?
Group of autosomal dominant genetic conditions arising from mutations in type 1 collagen
How many types of osteogenesis imperfecta are there?
Neonatal lethal - type 2
Very severe - type 3 and 4
Mild - type 1
What is osteogenesis imperfecta associated with?
How do severe forms present?
How is osteogenesis imperfecta treated?
Surgery for deformity