Osteoporosis Flashcards
What is osteoporosis?
Skeletal disease characterised by low bone mass and micro-architectural deterioration of bone tissue.
Leads to bone fragility
Describe the epidemiology of osteoporosis.
Estimated to develop osteoporisis:
1 in 3 females
1 in 8 males
Risk of fracture mainly depends on bone mineral density but absolute risk for any given individual is determined by factors such as age and risk of fall.
Incidence of fracture increases with age and is greater in females.
Give some risk factors for falls.
Poor balance postural hypotension muscle weakness poor vision cognitive impairment using sedative drugs.
What are the most common fracture sites?
Hip
Wrist
Spine
Describe the pathogenesis of Osteoporosis.
Bone mass = dynamic structure, bone formation dominates bone resorption until peak bone mass is achieved between 25 and 30 years of age.
Peak bone mass is determined by genetic and environmental factors such as nutrition and exercise as well as sex and lifestyle.
Bone resorption dominates over bone formation in postmenopausal women due to loss of oestrogen.
Exact mechanism unknown but oestrogen loss enhances osteoclast function.
Give examples of secondary causes of osteoporosis.
Liver disease Malabsorption Rheumatoid arthritis Excess alcohol Hyperthyroidism or hyperparathyroidism Smoking Oral or systemic steroids Prolonged bed-rest Low body mass index.
Bone resorption is more pronounced in hyperthyroidism, hyperparathyroidism and malnutrition.
Bone formation is impaired to greater extent in liver disease
Glucocorticoids decrease bone formation and increase bone resorption equally.
What clinical features would be present in osteoporosis?
Asymptomatic until a fracture occurs.
Hip and spine fractures are common in osteoporosis.
- Individuals may have acute back pain from vertebral fractures but many are asymptomatic, may be incidental finding on radiography.
- Vertebral fractures result in loss of height, dorsal kyphosis, contact between pelvis and ribs and a change in posture.
Rib fractures following minor trauma are fairly common.
What investigations would you perform for a patient with suspected osteoporosis?
Blood tests aimed at excluding secondary causes, may include: Renal and liver function Calcium Phosphate Alkaline phosphatase immunoglobulins ESR Thryoid function Endomysial antibodies (coeliac disease)
Radiography may show reduced bone density.
DEXA scan assesses bone mineral density.
Result reported as a difference in standard deviations from adult mean scores
-T scores. T score less than -2.5 =osteoporosis.
How do you manage osteoporosis?
Remember scoring system
Absolute fracture risk in any individual depends on age, bone density and risk for falls. Management depends on assessing these.
Normal bone density:
T score less than -1.0, fracture risk low, give lifestyle advice.
Osteopenia:
T score -1.5 to -2.5
Fracture risk above average.
Give lifestyle advice plus consider calcium and vit d supplements.
Osteoporosis:
T score less than -2.5
High fracture risk
Manage as for osteopenia but also consider giving drugs to improve bone density.
Must identify and manage secondary causes of osteoporosis.
Give examples of lifestyle changes that should be recommended in osteoporosis
Nutritional improvement
increasing physical activity
smoking cessation
avoiding heavy alcohol consumption.
Diet high in calcium or calcium supplements should be used as adjunct to other therapies.
What additional drugs could be used in osteoporosis if future fracture risk is high?
Bisphosphonates
- Group of synthetic analogues that inhibit bone resorption.
- eg alendronate, and risedronate
HRT should be considered in postmenopausal women and testosterone in hypogonadal men.
Pulsed parathormone injection may also improve bone density.
What is the difference between osteoporosis and osteomalacia?
In osteoporosis there is thinning and loss of trabecular plates.
In osteomalacia the total mass of bone may be normal but it is soft and weak as it is not properly mineralised.
In children osteomalacia is known as rickets.
