1: Metabolic Bone Disease Flashcards

1
Q

What is osteoporosis

A

condition where there is a decrease bone density leading to decrease bone strength

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2
Q

Which age group is most likely to develop osteoporosis

A

Elderly

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3
Q

In which gender is osteoporosis more common

A

Females (4:1)

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4
Q

What is the typical demographic affected by osteoporosis

A

Post-menopausal females

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5
Q

How can the aetiology of osteoporosis be divided

A

Primary

Secondary

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6
Q

What is type I primary osteoporosis

A

Post-menopausal osteoporosis

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7
Q

Explain briefly the pathophysiology of type I osteoporosis

A
  • Oestrogen activates osteoblasts and inhibits osteoclasts
  • At menopause oestrogen decreases
  • Drop in oestrogen increases osteoclast activity and decreases osteoblast activity
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8
Q

What is type II primary osteoporosis

A

Osteoporosis due to underlying disorder

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9
Q

How can the aetiology of secondary osteoporosis be divided

A
  • Iatrogenic
  • Endocrine
  • Other
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10
Q

What are 3 iatrogenic causes of secondary osteoporosis

A
  • PPI’s
  • Corticosteroids
  • Anti-epileptics
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11
Q

What 3 drugs can cause osteoporosis

A
  • PPI’s
  • Corticosteroids
  • Anti-epileptics
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12
Q

What are the 5 endocrine causes of osteoporosis

A
  • Hyperparathyroidism
  • Renal osteodystrphy
  • Hyperthyroidism
  • Cushing’s disease
  • Hypogonadism
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13
Q

Aside from endocrine and iatrogenic causes, what else may cause secondary osteoporosis

A
  • Alcohol abuse

- Immobilisation

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14
Q

What is a mneumonic to remember risk factors for osteoporosis

A

SHATTERED

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15
Q

what are the risk factors for osteoporosis

A
Steroid use 
Hyperparathyroidism, hyperthyroidism, hypercalciuria 
Alcohol abuse
Thin (BMI <18.5) 
Testosterone low
Early menopause 
Renal or liver failure 
Erosive or inflammatory disease
Diet malnutrition, T1DM
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16
Q

How will osteoporosis present clinically

A

asymptomatic. First presentation is typically with a fragility fracture

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17
Q

Order the following in most likely region to suffer from an osteoporotic fracture

A

Vertebral > Femoral neck > Colle’s fracture > long bone

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18
Q

how may vertebral fractures present

A
  • Acute back pain

- If multiple fractures may present with progressive shortening and thoracic kyphosis

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19
Q

if trabecular bone is affected , what type of fracture is more common

A

Vertebral

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20
Q

in which gender are trabecular fractures more common and why

A

Females. As males trabecular bone remains stable in time, whereas females loose trabecular bone with age

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21
Q

if cortical bone is affected, what fractures are more likely

A

Long bone

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22
Q

what investigations may be performed following an osteoporotic fracture

A
  1. X-Ray
  2. Fracture assessment tool (FRAX, Q Fracture)
  3. DEXA scan
  4. Bone profile
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23
Q

what tool is used to assess risk of fracture

A

FRAX (fracture risk assessment tool)

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24
Q

who is a FRAX score calculated for

A

All women >65y
All men >75y
Younger patients in presence of risk factors

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25
Q

what does FRAX score calculate

A

Individuals risk of osteoporotic fragility fracture in 10y

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26
Q

what age range is FRAX score suitable for

A

40-90

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27
Q

if FRAX shows an intermediate score what should be done

A

Bone mineral density score

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28
Q

If FRAX shows a good score, what should be done

A

No treatment

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29
Q

If FRAX shows a poor score, what should be done

A

Treat

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30
Q

Aside from FRAX, what is another tool used to assess risk of osteoporotic fracture

A

QFracture

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31
Q

what age can QFracture be used for

A

30-99

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32
Q

If a individual had their FRAX score calculated with bone mineral density and scores the following what should be done

a. low risk
b. intermediate risk
c. high risk

A

a. do not treat
b. consider treatment
c. treat

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33
Q

when should the FRAX score be re-assessed

A
  • After 2 years if individual was in ‘consider treatment’ but did not opt to
  • Change in person’s risk factors
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34
Q

What is used to assess bone mineral density

A

DEXA scan

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35
Q

what are 6 indications for DEXA scan

A
  1. Women >65y with one or more risk factors of osteoporosis
  2. Women <65y with two or more RF for osteoporosis
  3. Low trauma fracture
  4. Fragility fracture
  5. Starting long-term prednisolone
  6. Bone remodelling disorder
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36
Q

What dose of prednisolone should individuals be DEXA scanned before giving

A

> 5mg/d for 3m

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37
Q

What group of patients do not need a DEXA scan before treating

A

> 75y with two or more of the following: rheumatoid arthritis, alcohol abuse, FHx

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38
Q

What does a DEXA scan provide

A

T score

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39
Q

What is the T score

A

Provides number standard deviations individual is away from average bone mineral density of a 30y male

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40
Q

what does T>0 indicate

A

Better than reference

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41
Q

What does T: 0 to -1 indicate

A

In top 84% (normal healthy bone)

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42
Q

What does T: -1 to -2.5 indicate

A

Osteopenia

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43
Q

What does T: less than -2.5 indicate

A

Osteoporosis

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44
Q

What is a Z score

A

Bone mineral density compared to individual the same age

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45
Q

Why may a bone profile be requested in osteoporosis

A

To identify hyperparathyroidism, or other diseases.

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46
Q

What is first-line management for osteoporosis

A

lifestyle management

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47
Q

What 6 pieces of lifestyle advice would you provide someone with osteoporosis

A
  1. Smoking cessation
  2. Limit alcohol to <2 units
  3. Tai chi
  4. Weight bearing exercises
  5. Falls prevention program
  6. Calcium and vitamin D supplementation
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48
Q

Why is tai chi offered

A

To improve balance and help reduce falls

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49
Q

when are calcium and vitamin D supplementation offered

A

If evidence of deficiency

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50
Q

what is second-line management for osteoporosis

A

Aledronate (bisphosphonate)

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51
Q

what dose of alendronate is offered

A

10mg/d

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52
Q

what is a contraindication to aledronate

A

eGFR <35

53
Q

what other bisphosphonates may be used if the individual is intolerant to alendronate

A

risedrontate, etidronate

54
Q

What is third-line for management of osteoporosis

A

strontium ranelate

55
Q

why is strontium ranelate not first line

A

as it increases the risk of VTE and cardiovascular disease

56
Q

what are the requirements for strontium ranelate

A

> 60Y and T score -3.5 or less

57
Q

what is fourth-line for osteoporosis

A

Raloxifene

58
Q

what is raloxifene

A

selective oestrogen receptor modulator

59
Q

what is the benefit of raloxifene

A

it does not increase the risk of breast cancer

60
Q

what is the main disadvantage of raloxifene

A

increases VTE risk

61
Q

what is the criteria for raloxifene

A

Women >60y with a T score of less than -3.5

62
Q

what is 5th line management for osteoporosis

A

denosumab

63
Q

what is denosumab

A

RANKL monoclonal antibody

64
Q

how is denosumab given

A

subcutaneous injection twice a year

65
Q

what is the main complication of osteoporosis

A

fragility fractures

66
Q

What are the 4 fat soluble vitamins

A

A,D,E,K

67
Q

How can the causes of vitamin D deficiency be divided

A
  • Poor intake
  • Malabsorption
  • Poor metabolism
68
Q

What are 3 causes of vitamin D deficiency due to poor intake

A
  • Dark skin (reduces UV absorption)
  • Poor exposure to UVB
  • Poor dietary intake
69
Q

What are 3 causes of vitamin D deficiency due to malabsorption

A

Coeliac
Gastrectomy
Cystic fibrosis

70
Q

Why does cystic fibrosis cause malabsorption of vitamin D

A

Due to reduced absorption of fat soluble vitamins

71
Q

What are 4 causes of defective metabolism that lead to vitamin D deficiency

A
  • CYP450 inducers
  • Liver cirrhosis
  • Anticonvulsants
  • Renal disease
72
Q

Define osteoporosis

A

decreased bone mineral density

73
Q

Define osteopenia

A

decreased bone strength but less severe than osteoporosis

74
Q

What is T score

A

compares individuals mean mineral bone density to mean peak mass of a healthy young adult

75
Q

What T score indicates osteopenia

A

-1 to -2.5

76
Q

What T score indicates osteoporosis

A

less than -2.5

77
Q

What is the Z score

A

compares individuals mean mineral bone density to someone of the same age and gender

78
Q

What are 4 ways osteoporosis may present

A
  • Asymptomatic
  • Fragility fracture
  • Progressive shortening and thoracic kyphosis
  • Acute back pain
79
Q

What are 4 complications of osteoporosis

A
  • Vertebral fracture
  • Colle’s fracture
  • NOF fracture
  • Chronic pain syndrome
80
Q

What are 3 structural consequences on bone in osteoporosis

A
  1. Fewer trabeculae
  2. Thinner cortical bone
  3. Widening of haversian canals
81
Q

What is osteomalacia

A

insufficient mineralisation of bone

82
Q

what is the difference between osteomalacia and ricket’s disease

A

it is termed osteomalacia if it occurs after epiphysis have fused. And, ricket’s if before.

83
Q

how can the aetiology of osteomalacia be divided

A

vitamin D dependent and vitamin D independent

84
Q

how can causes of vitamin D deficiency be divided

A
  1. Insufficient intake
  2. Malabsorption
  3. Decreased metabolism
85
Q

how can vitamin D independent causes of osteomalacia be divided

A
  • Phosphate deficiency
  • Medication
  • Defects in renal tubule
    function
86
Q

what are two defects in renal tubule function that may lead to osteomalacia

A

Fanconi’s syndrome

Renal tubule acidosis

87
Q

What are 3 medications that could cause osteomalacia

A

Bisphosphonates
Aluminum
Fluoride

88
Q

How will osteomalacia present

A
  • Bone pain
  • Pathological fracture
  • Proximal myopathy
89
Q

What does proximal muscle weakness cause in osteomalacia

A

Waddling gait

90
Q

Explain how renal disease can lead to renal osteodystrophy

A
  • Renal dysfunction causes an inability to hydroxylate vitamin D to it’s active form.
  • Decreased vitamin D means insufficient absorption of calcium from the gut
  • Calcium deficiency causes secondary hyperparathyroidism
  • Increased PTH results in increased bone re-asborption
91
Q

Explain how phosphate deficiency causes osteomalacia

A

Decreased phosphate in the blood stream and hence available to form bone matrix

92
Q

What is first-line investigation of osteomalacia

A

Bone Profile

93
Q

What may be seen on bone profile in osteomalacia

A
  • Hypocalcaemia
  • Hypophosphataemia
  • Hyperparathyroidism
  • Low vitamin D
  • Raised ALP
94
Q

What is second-line investigation of osteomalacia

A

X-ray

95
Q

What finding on x-ray is pathognomic of osteomalacia

A

Looser’s pseudofractures

96
Q

what are looser’s pseudo fractures

A

Sclerotic lines perpendicular to cortical margins

97
Q

which 3 places are looser’s pseudo fractures most common

A
  • Lateral border of scapula
  • Inferior femoral neck
  • Medial femoral shaft
98
Q

what is first-line management for osteomalacia

A

Vitamin D and Calcium Supplementation

99
Q

if individual is dietary vitamin D deficient what should they be offered

A

Vitamin D3

100
Q

If individual has vitamin D deficiency due to hepatic disease, what form should they be offered

A

Ergocalciferol (Vitamin D2)

101
Q

what is the dose of ergocalciferol offered in hepatic disease

A

40,000 IU (1mg/day)

102
Q

if an individual has vitamin D deficiency due to renal disease what two forms can they be offered

A
  1. Alfacalcidiol (vitamin D2)

2. Calcitriol

103
Q

what is alfacalcidiol

A

1a hydroxyvitamin D3 (it has been hydroxylated once, so therefore only relies on liver to hydroxylate it a second time)

104
Q

what dose of alfacalcidiol is used

A

250mg/OD

105
Q

what is calcitriol

A

1,25 (OH) hydroxy vitamin D

106
Q

what dose of calcitriol is used

A

250mg/OD

107
Q

what could be used to increase serum calcium concentration as a second line

A

Calcium carbonate (1-2g/day)

108
Q

What is Paget’s disease also referred to

A

Osteitis deformans

109
Q

What is Paget’s disease

A

Increase bone turnover in focal parts of the skeleton associated with increased osteoblast and osteoclast activity causing resultant remodelling, enlargement, deformity and weakness

110
Q

What is a risk-factor for Paget’s Disease

A

Age. Typically onsets >55y

Male

111
Q

What are two risk factors for Paget’s disease

A

FHx

Northern latitude

112
Q

What % of patient’s with paget’s disease experience symptoms

A

10-30%

113
Q

If symptoms, what is commonly experienced

A

Bone pain

114
Q

If untreated, what are two severe presentations of Paget’s disease

A

Frontal Bossing

Bowing of the tibia

115
Q

What is the stereotypical presentation of paget’s disease

A

Old male with isolated raised ALP

116
Q

Explain pathology of Paget’s disease

A

Increased RANKL signalling increases NF-KB activity in osteoclasts. This increases osteoblast activity resulting in formation of dis-organised woven bone

117
Q

What are the 3 phases of bone remodelling in Paget’s disease

A
  1. Lytic
  2. Lytic and plastic
  3. Sclerotic
118
Q

What is the lytic phase

A

Increased osteoclast activity - increase bone reabsorption

119
Q

What is the lytic and blastic phase

A

Increased osteoclast activity is associated with an increase in osteoblast activity

120
Q

What is sclerotic phase

A

Decrease in both osteoblast and clast activity

121
Q

What are 2 investigations of Paget’s disease

A

Bone profile

X-ray

122
Q

What will be seen on bone profile in Paget’s disease

A

Isolated raised ALP

123
Q

How will bone appear on x-ray in Paget’s disease

A
  • Deformed bone with sclerotic and osteolytic lesions

- Thickened cortical bone

124
Q

How is Paget’s disease managed

A
  1. Analgesia (NSAIDs)

2. Bisphosphonates

125
Q

What bisphosphonates are offered for Paget’s disease

A

Oral riserdrontate

IV zoledronate

126
Q

What are 4 complications of Paget’s disease

A

Deafness
Sarcoma
Fractures
High output cardiac failure

127
Q

Why may Paget’s disease cause deafness

A

Due to enlargement of the skull trapping cranial nerve

128
Q

What are 4 most common sites of Paget’s disease to assert

A
  • Skull
  • Vertebrae
  • Pelvis
  • Long bones
129
Q

Why might paget’s disease cause high output cardiac failure

A

due to increased vascularity required by bone. (It is a rare complication)