Metabolic Bone disease 2 (Osteoporosis) Flashcards
What is 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 are risk factors for Osteoporosis
Older age
Female
Reduced mobility and activity
Low BMI (<18.5 kg/m2)
Rheumatoid arthritis
Alcohol and smoking
Long term corticosteroids.
Other medications such as SSRIs, PPIs, anti-epileptics and anti-oestrogens
What is a key group where osteoporosis should be considered.
Post-menopausal women because Oestrogen is protective against osteoporosis.
Unless they are on HRT postmenopausal women have less oestrogen. They also tend to be are older and often have other risk factors for osteoporosis.
What can you use to calculate the fracture risk of bones
FRAX tool
What is the FRAX tool
The FRAX tool gives a prediction of the risk of a fragility fracture over the next 10 years. This is usually the first step in assessing someone’s risk of osteoporosis.
How do you measure bone mineral density
Dual energy xray absorptiometry (DEXA)
What are Dual energy xray absorptiometry (DEXA)
DEXA scans are brief xray scans that measure how much radiation is absorbed by the bones, indicating how dense the bone is
Where do you scan with a DEXA
The bone mineral density (BMD) can be measured at any location on the skeleton, but the reading at the hip is key for the classification and management of osteoporosis.
How is Bone density can be represented in a DEXA
Z score
T score
What is a Z score
Z scores represent the number of standard deviations the patients bone density falls below the mean for their age.
What is a T score
T scores represent the number of standard deviations below the mean for a healthy young adult their bone density is.
What DEXA score forms the basis for the WHO classification of a level of osteoporosis
T score at the persons hip
What is the Epidemiology of Osteoporosis
I in 2 women over 50 will have an osteoporotic fracture before they die
I in 5 men over 50 will suffer and osteoporotic fracture
A 50 year old woman has a lifetime risk of 17% of a hip fracture
What can be done prophylactically to prevent fractures
Minimise risk factors
Ensure good calcium and
Vitamin D/calcium status
Falls prevention strategies
Medications
What is the first step in assessment of risk of osteoporosis
The first step is to perform a FRAX assessment on patients at risk of osteoporosis:
Who do you perform FRAX on
Women aged > 65
Men > 75
Younger patients with risk factors such as a previous fragility fracture, history of falls, low BMI, long term steroids, endocrine disorders and rheumatoid arthritis.
What is first line medication used in osteoporosis
Oral Bisphosphonates generally the first line of treatment
How do Bisphosphonates work?
They work by interfering with osteoclasts and reducing their activity, preventing the reabsorption of bone. There are a few key side effects to remember:
What are the side effects of Bisphosphonates
Reflux and oesophageal erosions.
Atypical fractures (e.g. atypical femoral fractures)
Osteonecrosis of the jaw
Osteonecrosis of the external auditory canal
How are Bisphosphonates taken?
Oral bisphosphonates are taken on an empty stomach sitting upright for 30 minutes before moving or eating to prevent this.
What are 3 bisphosphonate medications
Alendronate 70mg once weekly (oral)
Risedronate 35 mg once weekly (oral)
Zoledronic acid 5 mg once yearly (intravenous)
Apart from bisphosphonates what other medications can be used in osteoporosis
Denosumab
Strontium ranelate
Raloxifene
Hormone replacement therapy (HRT)
What is Denosumab
Denosumab is a monoclonal antibody that works by blocking the activity of osteoclasts.
What is Strontium ranelate
Strontium ranelate is a similar element to calcium that stimulates osteoblasts and blocks osteoclasts but increases the risk of DVT, PE and myocardial infarction.
What is Raloxifene
Raloxifene is used as secondary prevention only. It is a selective oestrogen receptor modulator that stimulates oestrogen receptors on bone but blocks them in the breasts and uterus.
What is Hormone replacement therapy
Hormone replacement therapy should be considered in women that go through menopause early.
