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Medicine Phase 2a MSK and Rheumatology > Osteoporosis > Flashcards

Osteoporosis Flashcards

1
Q

Describe

A

Progressive systemic skeletal disease
Characterised by low bone mass and a micro architectural deterioration of bone tissue
This increases bone fragility and susceptibility to fracture

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2
Q

Clinical presentation

A

Develops asymptomatically
Bone fragility
Fracture is often 1st sign (neck of femur)
Fractures in thoracic vertebrae may lead to kyphosis (abnormal excessive curvature of spine)

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3
Q

Pathophysiology

A

Inadequate peak bone mass, excessive bone resorption and inadequate formation of new bone during remodelling.
Increased osteoclast activity caused by:
Lack of oestrogen
Deficiency of calcium (increased bone resorption through PTH)
RANKL binds to RANK, activating osteoclasts
Steroids

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4
Q

Aetiology

A

Menopause
Nutritional deficiency contributes
Bone density naturally lost from 35 (Increasing age past around 35)
Steroids can activate osteoclasts

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5
Q

Epidemiology

A

More common in women, particularly after menopause.

Being thin

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6
Q

Diagnostic tests

A

Dual-energy X-ray absorptiometry (DEXA) scan and clinical diagnosis
X-ray can show fractures, therefore for osteoporosis but insensitive for osteopenia

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7
Q

Treatment

A

Prevent fractures
Calcium and vitamin D intake
*Bisphosphonates in those who have never had a fracture
Oestrogen supplement (Hormone Replacement Therapy) or testosterone for men; Raloxifene = Selective oestrogen receptor modulator
Recombinant human parathyroid peptide e.g. Teriparatide, increases osteoblast activity and bone formation

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8
Q

Complications

A

Fractures

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9
Q

What disease is the precusor to osteoporosis

A

Osteopenia

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10
Q

Define osteopenia

A 
Pre-cursor to osteoporosis characterised by low bone density
Defined as BMD between 1-2.5 standard deviations BELOW the young adult
mean value (-1< T score < 2.5)
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11
Q

Define osteomalacia

A

Poor bone mineralisation leading to soft bone due to lack of Ca2+ (adults form of Ricket’s)

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12
Q

What is T-score

A

The results of your bone density compared with those of a healthy young adult of the same sex as you, will be given as an osteoporosis T-score
Standard deviation score ascertained using a Dual Energy X-ray Absorptiometry (DEXA) scan
Which is then compared with the gender-matched young adult average (peak bone mass)

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13
Q

What is T-score range for each of these:
Normal
Osteopenia
Osteoporosis

A

Normal = no more than 1.0 (standard deviations) below normal average
Osteopenia -1.0 to -2.5
Osteoporosis = more than 2.5 below normal average

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14
Q

Risk factors of osteoporosis

A
  • Old age
  • Women
  • Family Hx of osteoporosis or fracture
  • Previous bone fracture
  • Smoking/Alcohol
  • SHATTERED
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15
Q

Risk factors of osteoporosis: SHATTERED

A

Steroid (prednisolone)
Hyperthyroidism/Hyperparathyroidism
Alcohol and tobacco
Thin (BMI <22)
Testosterone decreased (increased bone turnover)
Early menopause (drop in oestrogen)
Renal (or liver) failure
Erosive/inflammatory bone disease e.g. RA or myeloma
Dietary calcium decrease/malabsorption or Diabetes mellitus type 1

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16
Q

Which cytokines increase bone turnover

A

TNF - alpha

IL - 6

17
Q

Why does a low BMI increase your risk of osteoporosis

A

Reduced skeletal loading - increases bone resorption e.g. low body weight (obese people have higher bone density) and immobility

18
Q

Examples of endocrine disorders that increase risk of osteoporosis

A

Cushings - high cortisol - cortisol increases bone resorption (via osteoclasts)and induces osteoblast apoptosis
Hyperthyroidism and hyperparathyroidism - Thyroid hormone and parathyroid hormone increase bone turnover
Oestrogen and testosterone control bone turnover

19
Q

What is postmenopausal osteoporosis

A

Oestrogen deficiency after menopause
Resulting in increased numbers of osteoclasts, premature arrest of osteoblastic synthetic activity and perforation of
trabeculae
Loss of resistance to fracture
High bone turnover (resorption > formation)
Bone loss

20
Q

How does ageing increase risk of osteoporosis

A

Decrease in trabecular thickness - as we age the strain is felt on bones from head to tail, in response, we tend to preferentially preserve VERTICAL TRABECULAE and LOSE HORIZONTAL TRABECULAE.
Decrease in trabeculae thickness in connections between horizontal trabeculae resulting in decrease trabecular strength and increased susceptibly to fracture.

21
Q

Genes involved in osteoporosis

A

Collagen type 1A1
Vitamin D receptor
Oestrogen receptor genes

22
Q

How is bone strength determined

A

BMD (Bone mineral density) - quantity of mineral in bone, determine by quantity gained in growth and quantity lost in ageing
Bone size - short and fat is stronger than long and thin (distribution of cortical bone)
Bone quality - optimum range of mineralisation/turnover

23
Q

How would you diagnose a fracture

A

X-ray

24
Q

True or false:

Ca2+, phosphate and alkaline phosphate all normal on bloods

A

True

25
Q

What can be given to those intolerant to bisphosphonates

A

Strontium renelate - helps reduce fracture rates

26
Q

Benefits of hormone replacement theory (oestrogen)

A

(2nd line, used in menopausal women)
Reduces fracture risk and stops bone loss
Prevents hot flushes and other menopausal symptoms
Reduces colon cancer

27
Q

Side effects of HRT (oestrogen)

A

Breast cancer
Stroke
CVS disease

28
Q

*Example of Selective oestrogen receptor modulator (SERM) and how does it work

A

Raloxifene

Activates oestrogen receptor on bone whilst having no stimulatory effect on endometrium (similar to HRT)

29
Q

Side effects of SERM like raloxifene

A

Increased risk of thrombus formation, cramps and stroke

30
Q

How do bisphosphonates work

A

Inhibit bone resorption through inhibition of enzyme involved in osteoclast activity.
Enzyme = Farnesyl Pyrophosphate synthase (in cholestrol pathway and removes ruffled border of osteoclast)

31
Q

Example of bisphosphonate

A 
Oral aldendronate (most common)
IV zoledronate (once yearly)
32
Q

*What is Z score

A

Compares your bone density measurement with that of a healthy person that matches your sex, your age, your weight and your ethnic origin

33
Q

What is FRAX score

A

Your risk of having an osteoporosis-related fracture in the next 10 years

34
Q

What is DEXA scan

A

Dual-energy X-ray absorptiometry scan
Bone mass density assessment
Defined as bone mineral density (BMD) MORE than 2.5 standard deviations BELOW the young adult mean value (T score < 2.5)

Medicine Phase 2a MSK and Rheumatology (18 decks)

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