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Medical Studies 2A > 8.4 Bone Loss Conditions > Flashcards

8.4 Bone Loss Conditions Flashcards

1
Q

Describe the microscopic appearance of a spongy bone trabecule

A
  • Osteoclasts present
  • Osteocytes sitting in lacunae, connected to canaliculi
  • Lamellae (not concentric, though) sit in fibre. Strength of trabecule is proportional to square of diameter; more lamellae = more strength.
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2
Q

Describe the microscopic appearance of cortical bone

A
  • Blood vessels and nerves in haversian canal
  • Surrounding by concentric lamellae
  • Osteocytes in lacunae, connected by canaliculi
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3
Q

Compare the microscopic appearance of normal vs osteoporotic bone

A

Osteoporotic bone has much thinner trabeculae, and sometimes broken.

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4
Q

List as many risk factors for hip fractures as you can think of

A
  • Corticosteroids
  • Low BMI
  • Old age
  • Anticonvulsants (and seizures)
  • Rheumatoid arthritis
  • Low BMD
  • Smoking
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5
Q

What is the link between coeliac disease and osteoporosis?

A
  • Decreased area of gut
  • Decreased ability to absorb calcium
  • Therefore, decreased ability to regrow new bone
  • Osteoporosis
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6
Q

What is the link between inflammatory bowel disease and osteoporosis?

A
  • Decreased ability to absorb calcium
  • Medications such as corticosteroids increase risk
  • Inflammatory cytokines reduce bone density
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7
Q

How do kidney and liver disease cause osteoporosis?

A

Inability to convert vitamin D3 into calcidiol (liver) and calicitriol (kidney), leading to decreased calcium uptake.

(Kidney disease can also cause secondary hypoparathyroidism)

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8
Q

How does multiple myeloma cause osteoporosis? (and other cancers)

A
  • Myeloma cells produce osteoclast-activating cytokines
  • Increased bone breakdown
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9
Q

Why does hyperthyroidism cause osteoporosis?

A

Increased thyroxine can increase bone turnover.

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10
Q

Why does rheumatoid arthritis cause osteoporosis?

A

Increased inflammatory cytokines, decreased bone mass.

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11
Q

Explain why glucocorticoids (like cortisol) are so bad for your bone, using the 4 main aspects of damage

A
  1. Decreased GI Ca2+ absorption (inc. PTH)
  2. Decreased renal reabsorption of Ca2+
  3. Decreased sex steroid secretion
  4. Decreased osteoblast activity
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12
Q

What happens to mineral/non-mineral proportions in bone in osteoporosis, osteopaenia, and osteomalacia relative to normal?

A

Osteopaenia/porosis: same proportion, lower overall volume (-porosis moreso)

Osteomalacia: lower mineral content, normal non-mineral (hence Malakos = soft)

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13
Q

How does Paget’s disease differ from osteoporosis?

A
  • LOCALISED increase in bone turnover
  • Also, disorganised collagen
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14
Q

Which micronutrients are important in bone loss disease?

A
  • Vitamin D
  • Calcium
  • Phosphate
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15
Q

What T score is required for osteoporosis?

A

-2.5 or less

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16
Q

What is the diagnostic definition of a vertebral deformity?

A

20% or more decrease in height

17
Q

Why do we do a TSH test in osteoporosis workup?

A

Hypo can increase fall risk.

Hyper can cause increased bone loss.

18
Q

How long does it take, roughly, for osteoblasts to produce a new bone matrix during bone remodelling?

A

3 months

19
Q

Describe 3 aspects of non pharmacological management of osteoporosis

A
  1. Diet: get enough calcium
  2. Sun: get enough Vit D (very hard to get in food)
  3. Exercise: weight-bearing exercises
20
Q

List two antiresorptive drugs, and outline their mechanisms

A

Bisphosphonate: Taken up by osteoclasts, and impair action/increase apoptosis

Denosumab: monoclonal antibody that binds to RANKL, preventing osteoclast formation.

21
Q

What are some side effects of bisphosphonates? What else should we tell patients when prescribing them?

A
  • Upper GI (e.g. heartburn)
  • Acute phase (systemic inflammatory rxn)

Should be taken with water. Wait at least 30mins before eating after.

22
Q

Why should we be careful when deprescribing denosumab?

A

Bone density falls quicker after stopping than would be expected with bisphosphinates.

23
Q

Romosozumab is an antibody to which protein? What are the two effects of this? What must be considered when ceasing?

A
  • Sclerostin antibody
  • Decreases resorption, increases formation
  • Must prescribe antiresorptive upon cessation

Medical Studies 2A (108 decks)

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