Osteoporosis Flashcards

1
Q

what is bone remodelling?

A

where old bone is replaced by new bone
bone is an active tissue

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2
Q

what is bone remodelling controlled by?

A

osteoclasts and osteoblasts and osteocytes

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3
Q

what is bone resorption?

A

destruction of bone tissues leading to bone loss
-its where osteoclasts form cavities on bone surfaces

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4
Q

what is bone deposition?

A

-osteoblasts lay down new bone matrix
so formation of new bone

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5
Q

what is bone mineral density (BMD)?

A

-amount of minerals especially phosphorus and calcium in a bone volume

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6
Q

how does osteoporosis develop?

A

develops when bone resorption exceeds bone formation
-so when bone destruction is more than new bone formation

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7
Q

WHO definition for osteoporosis?

A

Bone mineral density above 2.5
AND
T-score of -2.5 or less

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8
Q

How is osteoporosis assessed?

A

Dual-energy X ray absorptiometry (DXA or DEXA)
-measures amount of bone at thoracolumbar spine, forearm, and hip
-measures bone mineral density

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9
Q

what is T-score?

A

compares patients bone mineral density to a healthy young adult
-osteoporosis = T-score = above 2.5

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10
Q

WHO CLASSIFICATION OF OSTEOPOROSIS

A

Normal = T-score = 1
Osteopaenia = T-score = -1 to -2.5
Osteoporosis = T-score = below -2.5
Severe osteopororsis = above -2.5

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10
Q

WHO CLASSIFICATION OF OSTEOPOROSIS

A

Normal = T-score = 1
Osteopaenia = T-score = -1 to -2.5
Osteoporosis = T-score = less than -2.5
Severe osteopororsis = above -2.5
the more negative score, the more severe osteoporosis

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11
Q

how is vitamin D converted to calcitriol?

A

Vitamin D3 is metabolised into (25-hydroxycholecalciferol) in liver.
then this is converted into CALCITRIOL known as (1,25-dihydroxycholecalciferol) in kidneys.

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12
Q

explain epidemiology of osteoporosis?

A

-High in white post-menopausal women
-white and asian women have equal risk
-Affects 1 in 3 women and 1 in 12 men in UK
-53% patients lose independence after hip fractures
-reduced quality of life and low self esteem from pain

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13
Q

what are the risk factors of osteoporosis?

A

Modifiable : smoking, excessive alcohol, low exercise, low calcium intake, low vit D
Non-modifiable : genetics, diabetes, rheumatoid arthritis, chronic liver disease

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14
Q

what are the primary causes of osteoporosis?

A

Primary causes:
-Female gender- reduced oestrogen levels so more bone loss. oestrogen plays important role in bone formation
-male gender - men have high bone mineral density so slower loss of BMD, fracture risk is less in men. men have shorter life expectancy.
-AGE - bone loss increases as age increases, low calcium and vit D intake from diet or sun. calcium and vit D important in bone health.

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15
Q

what are the secondary causes of osteoporosis?

A

-Premenopausal
-men younger than 70 years
- Drug induced - corticosteroids, thyroid hormone replacement drugs,
phenytoin increases vit D metabolism

16
Q

what are the non-pharmacological treatment?

A

-quit smoking
-reduce alcohol intake
-take vit D and calcium
-weight bearing exercise e.g. running, walking, jogging
-fall prevention - use canes, assess living environment
-warn about drugs that alter blood pressure/balance

17
Q

what are the pharmacological treatment for post-menopausal ostoporosis?

A

-Bisphosphonates -FIRST LINE!!! alendronate/risodranate
-HRT
-Calcitriol - if first line is unsuitable
-Raloxifene
-Parathyroid hormone- teriparatide

18
Q

what is the treatment for corticosteroid induced osteoporosis?

A
  • corticosteroids cause net bone loss and imbalance osteoblast and osteoclast activity
    -if patient used 7.5mg or more daily for 3-6 months
    -BISPHOPHONATE- FIRST LINE
    -HRT IN WOMEN -SECOND LINE
19
Q

Bisphosphonates for osteoporosis examples and MOA

A

-Alendronate
-Risedronate
-potent inhibitors of osteoclasts mediated bone resorption
-mimics effect of endogenous pyrophosphate
-reduces bone breakdown
-binds to hydroxyapatite crystals of bone so prevents bone growth and dissolution.

20
Q

Bisphosphonates DOSING/pharmacology

A

dosing: daily or once weekly 35mg
- half time is very long (many years)
-poorly absorbed after oral
-absorption may be reduced if given with food, antacids, calcium, iron containing drugs, tea and coffee
- Avoid eGFR below 35ml/min

21
Q

Key counselling points to give with bisphosphonate

A
  • Take on empty stomach- 30mins before breakfast with full glass of water
    -Do not take at bedtime
    -Stand or sit upright for 30 mins after taking the tablet
    -stop taking it if you develop dysphagia or new heartburn,
    -report thigh, hip, groin pain, dental pain, swelling, ear pain, ear infection/discharge
22
Q

HRT and their benefits on bone health

A

-HRT not recommended as first line -increases risk of breast cancer and blood clots
-there are oestrogen receptors on osteoclasts and osteoblasts
-oestrogen reduced osteoclast activity
-increases calcitriol concentration
-reduces renal calcium excretion
-reduces vertebral fracture risk

23
Q

calcitriol in ostoporosis

A

-active form of Vit D
-1,25 dihydroxycholecalciferol (vitamin D3)
-maintains calcium homeostasis
-increases plasma calcium levels
-decreases renal calcium excretion
-reduces bone loss and fracture risk
-treats post-menopausal osteoporosis

24
Q

Raloxifene pharmacology/dosing

A

-Selective oestrogen receptor modulator (SERM)
-treats post-menopausal osteoporosis
-has oestrogen agonist effect on bone
-increases bone mass
-well absorbed
-metabolised in liver
-undergoes first pass metabolism
-60mg DAILY
-Adverse effect: hot flush, VTE, leg cramps,

25
Q

what does raloxifene interact with?

A

anticoagulants
colestryramine - can reduce absorption of raloxifene
Caution: history of VTE, unexplained uterine bleeding, hepatic impairment, stroke

26
Q

what are the adverse effects of bisphosphonates

A

upper GI symptoms
abdominal pain
nausea
dyspepsia

27
Q

Teriparatide dosing and MOA

A

-improved Bone mineral density
-stimulates new bone formation
-enhances bone growth
-licensed for:
-postmenopausal osteoporosis in women
-corticosteroid induced in men and women
-men at increased risk of fractures

28
Q

denosumab in osteoporosis

A

human monoclonal antibody
-receptor activator of nuclear factor kappa-B ligand (RANKL)
-binds to RANKL inhibiting its action
-inhibits bone resorption
-adverse effects: skin infections, cellulitis, hypocalcaemia
- licensed use:
Treatment of postmenopausal osteoporosis in women and osteoporosis in men at an increased risk of fractures

29
Q

calcium and vit D supplement

A

-offer to ALL patients
-at least 1000mg calcium daily
-calcium carbonate contains highest amount of calcium
-most common side effect is constipation
-calcium reduces rate of bone loss
-800iu vit D + 1g calcium daily