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ENDOCRINE > Bone Disorders > Flashcards

Bone Disorders Flashcards

1
Q

What disease is characterised by a low bone mass causing skeletal fragility and susceptibility to fracture?

A

Osteoporosis

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2
Q

At what distinct sites does bone undergo remodelling?

A

bone remodelling units

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3
Q

What percentage of the adult skeleton is remodelled each year?

A

~10%

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4
Q

Briefly describe the bone remodelling cycle

A
  • osteoclasts appear on a previously inactive surface
  • resorb the bone
  • replaced by osteoblasts in the cavity
  • they put down osteoid that is mineralised to form new bone
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5
Q

Describe the ratio of osteoclasts to osteoblasts in osteoporosis

A

Osteoclasts>osteoblasts

=> more bone breakdown than formation

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6
Q

Describe the differences in micro-architecture between normal and osteoporotic bone

A

Osteoporotic:

  • clear loss of bone
  • large spaces and breaks
  • breaks lead to weakened bones and fractures

Normal bone:
- thick, dense network
- small spaces
=> increased bone strength

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7
Q

At what age do humans achieve their peak bone density?

A

Late 20s

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8
Q

Menopause causes slower age related bone loss. TRUE/FALSE?

A

FALSE

Menopause causes a period of accelerated bone loss

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9
Q

What are the most common fracture sites in osteoporosis?

A

Neck of femur
Vertebral body
Distal radius
Humeral neck

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10
Q

An older lady with osteoporosis falling onto an outstrectched hand is most likely to sustain what type of fracture?

A

Colles fracture

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11
Q

Wedge fractures of the spine can result in what curvature forming?

A

Thoracic Kyphosis

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12
Q

What scan is used to measure bone density?

A

DEXA scan

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13
Q

What bones are measured in a DEXA scan to assess bone density and why?

A

Hip
L1-L4
- as these are most prone to fracture -

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14
Q

Describe the difference between a T score and a Z score on the DEXA scan

A

T score = bone density compared to young adult population average

Z score = compared to population average of the same age as the patient

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15
Q

In what situation would only a Z score be considered ni a DEXA scan?

A

If the patient was <20 years old

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16
Q

How are DEXA results interpreted?

A

Normal if less than 1 standard deviation (SD) below the young adult average

Osteopenia if between 1 and 2.5 standard deviations below the young adult average

Osteoporosis if 2.5 or more standard deviations below

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17
Q

What does 1 standard deviation of seperation in a DEXA scan indicate in terms of fracture risk?

A

Lowering by 1 SD doubles fracture risk

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18
Q

What type of patients should be referred for a DEXA scan?

A

> 50 with low trauma fracture

If at increased risk:
e.g. > 10% risk of fracture over 10 years

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19
Q

What calculators are used to measure fracture risk in osteoporosis?

A

FRAX or Qfracture

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20
Q

The new SIGN guideline is no longer based on treating patients in terms of their mineral bone density. What is it more concerned about?

A

Fracture Risk

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21
Q

Give an example of a risk factor for a fragility fracture that is non-modifiable

A
  • Age
  • Gender
  • Ethnicity
  • Previous #
  • FHx
  • Menopause ≤ 45 years
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22
Q

What risk factors for fragility fractures are modifiable?

A
  • BMD
  • Alcohol
  • Weight/Physical inactivity
  • Smoking
  • Drugs (e.g. steroids)
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23
Q

What biochemical investigations should be considered in a patient who you are suspecting has osteoporosis

A

U+Es
LFTs
FBC and Plasma Viscosity
TSH

Consider:

  • Coeliac antibodies
  • 25OH Vitamin D
  • Parathyroid hormone
24
Q

What endocrine conditions are secondary causes of osteoporosis?

A

hyperthyroidism
hyperparathyroidism
Cushing’s disease

25
Q

What GI conditions cause secondary osteoporosis?

A

coeliac disease
IBD
chronic liver disease
chronic pancreatitis

26
Q

What respiratory conditions are linked to the development of secondary osteoporosis?

A

CF

COPD

27
Q

What lifestyle advice is used in management of osteoporosis?

A
  • High intensity strength training
  • Low-impact weight-bearing exercise
  • Avoidance of excess alcohol/smoking
  • Fall prevention
28
Q

How much calcium should post-menopausal women aim to eat per day in order to reduce their fracture risk?

A

1000 mg calcium (3-4 portion calcium rich foods)

29
Q

What non-dairy foods are considered sources of calcium?

A

Non-dairy sources include

  • bread and cereals (fortified)
  • fish with bones, nuts,
  • green vegetables, beans
30
Q

What drug treatments are often given in osteoporosis?

A
  • Calcium & Vit D supplements
  • Bisphosphonates
  • Denosumab (monoclonal antibody)
  • Teriparatide (Parathyroid hormone anabolic agent)
  • HRT
  • SERMS (Selective Estrogen Receptor Modulators)
  • Testosterone
31
Q

How far apart should patients be taking their oral bisphosphonates and their calcium supplements?

A

Calcium supplements should not be taken within 2 hours of oral bisphosphonates

32
Q

Give examples of Bisphosphonates

A

alendronate

risedronate

33
Q

How do bisphosphonates work?

A

They are ingested by osteoclasts
cause cell death
=> restoring Osteoclast:osteoblast ratio

34
Q

How long should patients remain on bisphosphonates?

A

benefit for 5 years (10 y if vertebral fracture)

Patients may also benefit from a period of no bisphosphonates

35
Q

What complications may present if patients remain on Bisphosphonates long term?

A

osteonecrosis of the jaw
oesophageal Ca
atypical fractures

36
Q

How is Zoledronic Acid administered?

A
  • Once yearly IV infusion for 3 years
  • 5 mg in 100 ml NaCl over 15 mins
  • *can cause acute phase reaction on first infusion**
37
Q

How does Denosumab work?

A

Monoclonal Antibody
inhibits development and activty of osteoclasts
=> prevents bone resorption

38
Q

How is Denosumab administered?

A

Subcutaneous injection 6 monthly

39
Q

What are the adverse effects of Denosumab?

A

Hypocalcaemia
eczema
cellulitis

40
Q

Teriparatide mainly aims to stimulate bone growth rather than reduce bone loss. TRUE/FALSE?

A

TRUE

41
Q

Describe the direct and indirect effects of corticosteroids on bone

A

DIRECT:

  • Reduce osteoblast activity and lifespan
  • Suppress replication of osteoblast precursors
  • Reduce Ca absorption

INDIRECT:
- Inhibit gonadal and adrenal steroid production

42
Q

What areas of the body do glucocorticoids act upon?

A

Bone
Kidney
Gut
Pituitary

43
Q

Describe the activity of both osteoclasts and osteoblasts in Paget’s disease

A

Abnormal osteoclastic activity

increased osteoblastic activity

44
Q

Describe the structure of bone developed in Paget’s disease

A

Abnormal bone structure with reduced strength and increased fracture risk

45
Q

Can Paget’s disease present in more than one site?

A

Yes

  • single site (monostotic)
  • multiple sites (polyostotic)
46
Q

What areas of bone are most affected by Paget’s disease?

A

long bones
pelvis
lumbar spine
skull

47
Q

How does Paget’s disease usually present?

A

bone pain
deformity
deafness
compression neuropathies

48
Q

What condition is a rare complication of Paget’s disease?

A

Osteosarcoma

49
Q

What scan can be used to show the distribution of Paget’s disease?

A

isotope bone scan

50
Q

If the pain in Paget’s disease does not respond to analgesia, what medication can be used?

A

Bisphosphonates

51
Q

What complications can patient’s develop in Paget’s disease?

A

Bowing of femur/tibia
Deaf if skull involvement
curved spine

52
Q

What genes are associated with the development of Paget’s disease and what do the encode?

A

mutations of type 1 collagen genes
COL1A1
COL1A2

53
Q

How is Paget’s disease inherited?

A

Autosomal Dominant Inheritance

54
Q

What other clinical signs are noted in severe forms of Osteogensis Imperfecta?

A

blue sclerae

dentinogenesis imperfecta

55
Q

Describe the difference in age of presentation of mild to severs osteogenesis imperfecta

A

Mild - May not present until adulthood

Severe - usually present in childhood due to fractures having already occurred

56
Q

What treatments are used in Osteogenesis Imperfecta?

A
  • fracture fixation
  • surgery to correct deformities
  • bisphosphonates
57
Q

What differential diagnosis should always be considered in a child presenting with a fracture that you think may be OI?

A

Non-accidental Injury

ENDOCRINE (22 decks)

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