Disease of the Bone Flashcards
Osteoporosis is a disorder affecting the skeletal system characterised by
loss of bone mass.
Bone mineral density decreases with age
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World Health Organisation define osteoporosis as
presence of bone mineral density (BMD) of less than 2.5 standard deviations (SD) below the young adult mean density.
Around?% of post-menopausal women will suffer an osteoporotic fracture at some point.
Around 50% of post-menopausal women will suffer an osteoporotic fracture at some point.
The major risk factors for osteoporosis are age and female gender.
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Guidelines recommend using a screening tool such as
FRAX or QFracture to assess the 10-year risk of a patient developing a fragility fracture. A patient who has sustained a fragility fracture (e.g. following a Colles’ wrist fracture) should also be assessed for osteoporosis.
To assess the actual bone mineral density what is used?
dual-energy X-ray absorptiometry (DEXA) scan is used. The DEXA scan looks at the hip and lumbar spine. If either have a T score of < -2.5 then treatment is recommended.
The first-line treatment for osteoporosis is
oral bisphosphonate such as alendronate. Other treatments are available but the vast majority of patients are managed with this therapy.
Osteoporosis the first list we should order the following bloods as a minimum for all patients:
full blood count urea and electrolytes liver function tests bone profile CRP thyroid function tests
risk factors that are used by major risk assessment tools such as FRAX:
history of glucocorticoid use rheumatoid arthritis alcohol excess history of parental hip fracture low body mass index current smoking
Medications that may worsen osteoporosis (other than glucocorticoids):
SSRIs antiepileptics proton pump inhibitors glitazones long term heparin therapy aromatase inhibitors e.g. anastrozole
In terms of body systems - what can be a risk for osteoporosis
endocrine disorders: hyperthyroidism, hypogonadism (e.g. Turner’s, testosterone deficiency), growth hormone deficiency, hyperparathyroidism, diabetes mellitus
multiple myeloma, lymphoma
gastrointestinal disorders: inflammatory bowel disease, malabsorption (e.g. Coeliac’s), gastrectomy, liver disease
chronic kidney disease
osteogenesis imperfecta, homocystinuria
Which ethnicity higher risk OP
Caucasians and Asians
If a patient is diagnosed with osteoporosis or has a fragility fracture further investigations may be warranted. NOGG recommend testing for the following reasons:
exclude diseases that mimic osteoporosis (e.g. osteomalacia, myeloma);
identify the cause of osteoporosis and contributory factors;
assess the risk of subsequent fractures;
select the most appropriate form of treatment
The risk of osteoporosis is thought to rise significantly once a patient is taking the equivalent of
prednisolone 7.5mg a day for 3 or more months
if it likely that the patient will have to take steroids for at least 3 months then we should start bone protection straight away, rather than waiting until 3 months has elapsed.
true
a patient with newly diagnosed polymyalgia rheumatica. As it is very likely they will be on a significant dose of prednisolone for greater than 3 months what should be commenced immediately.
bone protection
Management of patients at risk of corticosteroid-induced osteoporosis
The RCP guidelines essentially divide patients into two groups:
- Patients over the age of 65 years or those who’ve previously had a fragility fracture should be offered bone protection.
- Patients under the age of 65 years should be offered a bone density scan, with further management dependent
Management of patients at risk of corticosteroid-induced osteoporosis &
Patients under the age of 65 years
bone scan results & management???
Greater than 0: Reassure
Between 0 and -1.5: Repeat bone density scan in 1-3 years
Less than -1.5: Offer bone protection
The first-line treatment is alendronate. Patients should also be calcium and vitamin D replete.
Osteoporosis: assessing risk
all women aged ? years and all men aged ? years should be assessed
all women aged >= 65 years and all men aged >= 75 years should be assessed
Osteoporosis: assessing risk when should younger patients be assessed?
previous fragility fracture, history of falls, family history of hip fracture
current use or frequent recent use of oral or systemic glucocorticoid
low body mass index (BMI) (less than 18.5 kg/m²)
smoking
alcohol intake of more than 14 units per week for women and more than 14 units per week for men.
NICE recommend using a clinical prediction tool such as ? to assess a patients 10 year risk of developing a fracture
FRAX or QFracture
Describe FRAX
estimates the 10-year risk of fragility fracture
valid for patients aged 40-90 years
based on international data so use not limited to UK patients
assesses the following factors: age, sex, weight, height, previous fracture, parental fracture, current smoking, glucocorticoids, rheumatoid arthritis, secondary osteoporosis, alcohol intake
bone mineral density (BMD) is optional, but clearly improves the accuracy of the results.
NICE recommend arranging a DEXA scan if FRAX (without BMD) shows an intermediate result
Describe Qfracture
estimates the 10-year risk of fragility fracture
developed in 2009 based on UK primary care dataset
can be used for patients aged 30-99 years (this is stated on the QFracture website, but other sources give a figure of 30-85 years)
includes a larger group of risk factors e.g. cardiovascular disease, history of falls, chronic liver disease, rheumatoid arthritis, type 2 diabetes and tricyclic antidepressants
There are some situations where NICE recommend arranging BMD assessment (i.e. a DEXA scan) rather than using one of the clinical prediction tools for assessing osteoporosis risk
these are?
before starting treatments that may have a rapid adverse effect on bone density (for example, sex hormone deprivation for treatment for breast or prostate cancer).
in people aged under 40 years who have a major risk factor
, such as history of multiple fragility fracture, major osteoporotic fracture, or current or recent use of high-dose oral or high-dose systemic glucocorticoids (more than 7.5 mg prednisolone or equivalent per day for 3 months or longer).
If the FRAX assessment was done without a bone mineral density (BMD) measurement the results (10-year risk of a fragility fracture) will be given and categorised automatically into one of the following:
low risk: reassure and give lifestyle advice
intermediate risk: offer BMD test
high risk: offer bone protection treatment
If the FRAX assessment was done witha bone mineral density (BMD) measurement the results (10-year risk of a fragility fracture) will be given and categorised automatically into one of the following:
reassure
consider treatment
strongly recommend treatment
If you use QFracture instead patients are not automatically categorised into low, intermediate or high risk. Instead the ‘raw data’ relating to the 10-year risk of any sustaining an osteoporotic fracture. This data then needs to be interpreted alongside either local or national guidelines, taking into account certain factors such as the patient’s age.
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NICE recommend that we recalculate a patient’s risk (i.e. repeat the FRAX/QFracture):
if the original calculated risk was in the region of the intervention threshold for a proposed treatment and only after a minimum of 2 years, or
when there has been a change in the person’s risk factors
Describe DEXA scan - what does each score mean
T score: based on bone mass of young reference population
T score of -1.0 means bone mass of one standard deviation below that of young reference population
Z score is adjusted for age, gender and ethnic factors
