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Endocrine > Disorders of Bone Health > Flashcards

Disorders of Bone Health Flashcards

1
Q

What is osteoporosis?

A

Progressive systemic skeletal tissue disease characterised by low bone mass and microarchitecture deterioration of bone tissue

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2
Q

What occurs due to osteoporosis?

A

Increased bone fragility and susceptibility to fractures

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3
Q

What is the natural deterioration of bone over time?

A

20 years = strong, healthy bone
50 years = decreases in trabecular thickness which is more pronounced for non-loading horizontal trabeculae
80 years = decrease in number of connections between vertical trabeculae, decrease in trabecular strength

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4
Q

Where does bone remodelling take place?

A

At distinct sites called bone remodelling units = 10% of adult skeleton is remodelled each year

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5
Q

What does bone remodelling contribute to?

A

Calcium homeostasis and skeletal repair

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6
Q

What role do bone cells play in remodelling?

A 
Osteoclasts = activation and resorption
Osteoblasts = form bone
Osteoid = undergoes mineralisation
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7
Q

What are the regulating factors of osteoporosis?

A

Peak bone mass and bone loss

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8
Q

What are some contributors to peak bone mass, and when is it achieved?

A

Genetics (70-80%), body weight, sex hormones, diet, exercise, achieved by age 30

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9
Q

What are some determinants of bone loss, and when does it begin?

A

Sex hormone deficiency, body weight, genetics, diet, immobility, disease, drugs (glucocorticoids), occurs from age 45

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10
Q

Where are some common fracture sites in patients with osteoporosis?

A

Neck of femur, vertebral body, distal radius, humeral neck

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11
Q

How is bone density assessed?

A

BMD predicts fracture risk independently of other risk factors = most commonly measured using DEXA scans

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12
Q

What is the normal value for BMD?

A

Within 1SD of the young adult reference mean

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13
Q

What value of BMD is suggestive of osteopenia?

A

BMD >1SD below the young adult mean but <2SD below this value

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14
Q

What BMD is suggestive of osteoporosis and severe osteoporosis?

A 
Osteoporosis = BMD >= 2SD below young adult mean
Severe = BMD >= 2SD below young adult mean with fragility fracture
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15
Q

Which patients should be referred for a DEXA scan?

A

Patients >50 with low trauma fractures

Patients at increased risk of fracture based on risk factors

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16
Q

What patients with osteoporosis should be targeted for therapeutic intervention?

A

Those at high risk of low impact fractures

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17
Q

What are the SIGN 142 guidelines for osteoporosis based on?

A

Fracture risk = address risk factors for fractures (modifiable/non-modifiable), assessment of fracture risk

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18
Q

What are some non-modifiable risk factors for fractures in patients with osteoporosis?

A

Age, gender, ethnicity, previous fracture, family history, menopause <=45 years old, co-existing disease

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19
Q

What are some modifiable risk factors for fractures in patients with osteoporosis?

A

BMD, alcohol, weight, smoking, physical inactivity, pharmacological risk factors

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20
Q

How does the WHO risk calculator for fractures assess risk?

A

Calculation of absolute risk by incorporating additional risk factors = prediction of 10 year fracture risk of major osteoporotic fracture or hip fracture

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21
Q

What is used rather than BMD in patient’s under 20 with osteoporosis?

A

Z score

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22
Q

What patients are suitable for risk factor assessment?

A

Anyone >50 with risk factors, anyone <50 with very strong clinical risk factors (e.g early menopause)

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23
Q

When does risk assessment qualify osteoporosis patients for DEXA?

A

Anyone with a 10 year risk assessment for any osteoporotic fracture of at least 10%

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24
Q

What is investigated in patients with suspected osteoporosis?

A

U & Es, LFTs, bone biochemistry, FBC, PV, TSH

Consider protein electrophoresis/Bence Jones proteins, coeliac antibodies, testosterone, vitamin D, PTH

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25
Q

What are some secondary causes of osteoporosis?

A

Hyperthyroidism, hyperparathyroidism, Cushing’s disease, coeliac, IBD, chronic liver disease, chronic pancreatitis, CF, COPD, chronic kidney disease

26
Q

What is some lifestyle advice for patients with osteoporosis?

A

High intensity strength training, low impact weight-bearing exercise, avoidance of excess alcohol and smoking, fall prevention

27
Q

How much calcium should patients with osteoporosis aim to include in their diet per day?

A

700mg (2-3 portions)

Post-menopausal women aim for 1000mg to reduce fracture risk

28
Q

What are some non-dairy sources of calcium?

A

Bread, cereals (fortified), fish with bones, nuts, green vegetables, beans

29
Q

What are some drug treatments used for osteoporosis?

A

Calcium and vitamin D supplements, bisphosphonates, denosumab, teriparatide, HRT, testosterone

30
Q

When should calcium and vitamin D supplements be considered?

A

To reduce risk of non-vertebral fractures in patients who are at risk of deficiency due to insufficient dietary intake or limited sunlight exposure

31
Q

What is the rule when taking calcium supplements and oral bisphosphonates?

A

Calcium supplements must not be taken within 2hrs of oral bisphosphonates

32
Q

Is calcium supplementation needed if dietary intake in adequate?

A

No = only prescribe vitamin D in this case

33
Q

What are bisphosphonates?

A

Analogues of pyrophosphate that absorb onto bone within the matrix = ingested by osteoclasts leading to cell death (inhibit bone resorption)

34
Q

How do bisphosphonates improve BMD?

A

Filling of resorption sites by new bone increases BMD by 5-8%

35
Q

What are some anti-resorptive bisphosphonates?

A

Alendronate and risedronate = reduce risk of fragility fractures by 50% in patients with post-menopausal osteoporosis

36
Q

How do bisphosphonates help in osteoporosis?

A

Prevent bone loss in all sites vulnerable to osteoporosis, reduce risk of hip and spine fracture

37
Q

What is the number needed to treat (NNT) of bisphosphonates for one year to prevent one fracture in osteoporosis patients?

A

T score less than -2.5 = 150

Plus existing fragility fracture = 30

38
Q

What are the long term concerns of bisphosphonate use?

A

Osteonecrosis of jaw, oesophageal cancer, atypical fractures

39
Q

What is an example of an IV bisphosphonate?

A

Zoledronic acid = once yearly IV infusion for three years

40
Q

What is denosumab?

A

Fully human monoclonal antibody = targets and binds with high affinity and specificity to RANKL (receptor activator of nuclear factor-kB ligand)

41
Q

What does denosumab inhibit?

A

Prevents RANK activation = inhibits development and activity of osteoclasts which decreases done resorption and increases bone density

42
Q

How is denosumab administered?

A

Subcutaneous injection 6 monthly

43
Q

What are some adverse effects of denosumab?

A

Hypocalcaemia, eczema, cellulitis

No contraindication in severe renal impairment

44
Q

What is teriparatide?

A

Recombinant parathyroid hormone (1-34) = stimulates bone growth (anabolic agent)

45
Q

When is teriparatide used?

A

In severe osteoporosis, particularly if high risk of vertebral fracture

46
Q

When should medication be considered to treat osteoporosis?

A

Consider antiresorptive therapy when T score <= -2.5

47
Q

When should medication be started to treat osteoporosis patients with a T score < -1.5?

A

If the patient is has ongoing steroid requirement >= 7.5mg prednisolone for 3 months or more
If there is prevalent vertebral fracture

48
Q

What are the direct effects of corticosteroids on bone?

A

Reduction of osteoblast activity and lifespan, suppression of replication of osteoblast precursors, reduction in calcium absorption

49
Q

What is the indirect effect that corticosteroids have on bone?

A

Inhibition of gonadal and adrenal steroid production

50
Q

How do corticosteroids impact fracture risk?

A

Individual variability to glucocorticoids, dose-dependent (but no “safe” dose), rapid loss of BMD (30% in first 6 months), partially reversible on cessation

51
Q

What occurs in Paget’s disease?

A

Abnormal osteoclastic activity followed by increased osteoblastic activity = causes abnormal bone structure with reduced strength and increased fracture risk

52
Q

What are some features of Paget’s disease?

A

Unknown aetiology, Rare < age 40, incidence increases with age, may be single site (monostotic) or multiple sites (polystotic)

53
Q

What bones are typically affected in Paget’s disease?

A

Long bones, pelvis, lumbar spine, skull

54
Q

What are the signs and symptoms of Paget’s disease?

A

Bone pain, deformity, deafness, compression neuropathies, osteosarcoma may be rare complication

55
Q

How is Paget’s disease diagnosed?

A

Using x-ray = may be incidental finding

May be isolated high alkaline phosphatase

56
Q

What is the classic x-ray appearance of Paget’s disease?

A

Isotope bone scan shows expanded bone with coarsened trabecular pattern

57
Q

What is osteogenesis imperfecta?

A

Rare group of genetic disorders mainly affecting bone = most are autosomal dominant, most are secondary to mutations of type 1 collagen genes (COL1A1, COL1A2)

58
Q

How many types of osteogenesis imperfecta are there?

A

At least 8 types of varying severity = type 1 is mild, type 2 is neonatal (lethal), types 3 and 4 are very severe

59
Q

What may be osteogenesis imperfecta be associated with?

A

Blue sclerae and dentinogenesis imperfecta
More sever forms present with fractures in childhood
Mild forms may not present until adulthood

60
Q

What is the treatment options for osteogenesis imperfecta?

A

No cure = fracture fixation, surgery to correct deformities, bisphosphonates

Endocrine (42 decks)

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