Bone Health and Osteoperosis Flashcards
osteoporosis
condition in which bone density decreases due to reduced osteoblast activity, resulting in reduced bone mineral density, increased porosity and brittle bones which fracture easily
where are common fracture sites
neck of femur, vertebral body, distal radius and humeral neck
epidemiology of osteoporosis
increase in fractures in the elderly, partially due to poort stability and gait
women
why are women more prone to osteoporosis
lower peak bone mass, and accelerated loss of bone during the menopause
increased longevity
why is there an increase in osteoporosis post menopause
oestrogen promotes the activity of osteoblasts, there are lower levels post menopause
OCP can be used as prevention
name some secondary causes of osteoporosis
- Endocrine e.g. hyperthyroidism, hyperparathyroidism, Cushing’s disease
- G.I. e.g. coeliac, IBD, chronic liver disease, chronic pancreatitis
- Respiratory e.g. COPD
- Chronic kidney disease
- High alcohol intake
- Smoking
pathology of osteoporosis
bone undergoes constant remodelling, this contributes to calcium homeostasis and also skeletal repair
in osteoporosis there is reduced osteoblast activity
how much of the adult skeleton is remodelled every year
around 10%
type 1 and 2 osteoporosis
type 1 is post menopausal, due to increased osteoclastic activity
type 2 is osteoporosis of old age/steroids/alcohol/malnutrition/RA
describe the changes in bone mass with age
increase until peak around 30
slow rate of bone loss starts at around 40
what factors is peak bone mass influenced by
genetics (70-80%)
body weight
sex hormones
diet
exercise
what factors is bone loss influenced by
sex hormone deficiency (post menopause)
body weight
genetics
diet
immobility
diseases
drugs (eg steroids, aromatase inhibitors)
who is therapeutic intervention targeted at
those with a high risk of a low impact fracture
clinical risk factors for fragility fractures
Non-modifiable:
- Age
- Gender
- Ethnicity
- Previous fracture
- FH
- Early menopause (≤45 years)
Modifiable:
- BMD
- Alcohol
- Weight
- Smoking
- Physical inactivity
Also, co-existing diseases and pharmacological risk factors.
QFracture risk calculator pros and cons
- Incudes more variables e.g. dementia, PD, medications
- Allows smoking and alcohol to be given in quantities
- Considers history of falls/nursing home residence
- However, doesn’t include BMD
WHO FRAX risk calculator pros and cons
- Takes into account bone mineral density (DEXA scan)
- Gives a prediction of 10-year risk of major osteoporotic fracture or hip fracture
- However, underestimates vertebral fracture risk, assigns the same level of risk to all secondary causes, and there is a lack of clarity regarding the algorithm and the population used
who should have their fracture risk assessed
anyone >50 with risk factors
anyone <50 with very strong clinical factors eg early menopause, steroids
when to refer for DEXA from fracture risk calculator?
anyone with a 10 year risk assessment for any osteoporotic fracture of at least 10%
bone mineral density scan
predicts fracture risk independently of other risk factors
DEXA scans are the most widely used
normal BMD T score
within 1 SD of adult reference mean
osteopenia BMD T score
BMD 1-2.5 SD below young adult mean
there is a risk of later osteoporotic fracture, so offer lifestyle advice
osteoporosis BMD T score
≥2.5 SD below young adult mean
severe osteoporosis = “” with fragility fracture
what is used in BMD scans if the patient is under 20
only the Z score is reported
management of osteoporosis
high intesity strength training
low impact weight bearing exercises
avoidance of alcohol and smoking
fall prevention
dietary management of osteoporosis
- RNI 700mg Calcium
- Postmenopausal women aim for dietary intake of 1g Calcium per day to reduce fracture risk
- Calcium is also in fortified bread and cereals, nuts, beans etc.
calcium and vitamin D for osteoporosis treatment
- Supplements may be considered due to reduce non-vertebral fracture risk in patients who are at risk of deficiency due to insufficient dietary intake/limited sun exposure
- Calcium supplements should not be taken within 2 hours of oral Bisphosphonates
- If dietary Calcium is adequate (>700mg daily), only vitamin D may be required as the osteoporosis treatment adjunct
how to biphosphonates work
analogues of pyrophosphate that adsorb onto bone within the matrix and inhibit osteoclast acitivty by killing them (anti-resorptive)
prevent bone loss at all vulnerable sites and reduce the risk of hip and spine fractures
1st line biphosphonate
alendronate
risedronate
what are the long term consequences of biphosphonate use
- fractures eg femoral shaft, subtrochanteric
- there is evidence that they have a benefit for 5 years (10 in vertebral)
- one may want to consider a bone holiday
what are some other drug treatments available for osteoporosis
zoledronic acid
denosumab
teriparatide
how is zoledronic acid adminstered
once yearly infusion for 3 years
1 in 3 have an acute phase reaction with 1st infusion - give paracetamol
denosumab mechanism of action
inhibits development and activity of osteoclasts, decreasing bone resoprtion and increasing bone density
what is teriparatide
recombinant PTH
who is teriparatide used in
those who suffer further fractures despite treatment with other agents
stimulates a bone growth factor rather than reducing bone loss - anabolic agent
at what T score should treatment be commenced
≤-2.5
(1-2.5 is osteopenia, offer lifestyle advice)
when should one consider treatment with a T score of ≤-1.5
ongoing steroid treatmnet, preveleant vertebral fracture
what can be used for prevention of osteoporosis in long term steroid use
bisposphonates
