Biochemical Disorders of Bone Flashcards

1
Q

What characterizes osteoporosis?

A

reduced bone mineral density

increased porosity

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2
Q

What is bone mineral density of osteoporosis defined as in terms of standard deviations below the mean?

A

less than 2.5 standard deviations below the mean

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3
Q

What is bone mineral density of osteopenia defined as in terms of standard deviations below the mean?

A

between 1-2.5 standard deviations below the mean

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4
Q

When does loss of bone mineral density tend to occur?

A

30 yrs

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5
Q

Why do women tend to lose more bone mineral density after the menopause?

A

increase in osteoclastic bone resorption due to loss of protective effects of oestrogen

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6
Q

What are the two types of primary osteoporosis?

A

Type 1 = post menopausal

Type 2 = osteoporosis of old age

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7
Q

What are the added risk factors in type 2 osteoporosis?

A

sunlight exposure reduced, chronic disease, inactivity

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8
Q

What type of fractures tend to occur in type 1 osteoporosis?

A

colles fractures

vertebral insufficiency fractures

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9
Q

What type of fractures tend to occur in type 2 osteoporosis?

A

femoral neck fractures

vertebral fractures

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10
Q

What can osteoporosis occur secondary to?

A

alcohol abuse, steroid use, malnutrition, chronic disease eg CKD, malignancy, RA and endocrine disorders (Cushings, hyperthyroid, hyperparathyroid)

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11
Q

How is osteoporosis diagnosed?

A

DEXA scanning

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12
Q

What happens to serum calcium and phosphate in osteoporosis?

A

are normal

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13
Q

Can any treatment s increase BMD?

A

no

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14
Q

What is the mainstay of treatment in osteoporosis?

A

slow any further deterioration/decrease fracture risk

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15
Q

How can peak bone mineral density be built up?

A

exercise, healthy lifestyle

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16
Q

What treatments are used to try to prevent fractures?

A

calcium and vit D supplements, bisphosphonates, Desunomab and strontium

17
Q

What do bisphosphonates do?

A

reduce osteoclastic resorption

18
Q

What are examples of bisphosphonates?

A

end in ate eg alendronate

19
Q

What does strontium do?

A

increases osteoblast replication and reduces resorption

20
Q

Is HRT a first line agent for prevention of osteoporosis after menopause?

A

No but can be considered if side effects with other medications occur

21
Q

What are risks of HRT?

A

increast breast cancer/endometrial cancer rates

DVT

22
Q

Does raloxifene (oestrogen receptor modulator) have a risk of DVT?

23
Q

What currently have the greatest evidence for efficacy, cost effectiveness and low side effect profile in terms of osteoporosis treatment?

A

bisphosphonates

24
Q

What is osteomalacia?

A

qualitative defect of bone with abnormal softening of bone

25
What are there inadequate amounts of in osteomalacia?
calcium and phosphorus
26
What is the same as osteomalacia?
rickets
27
What may cause hypophosphataemia (a cause of osteomalacia)?
re feeding syndrome, alcohol abuse, malabsorption, renal tubular acidosis
28
What may patients complain of in osteomalacia?
bone pain, deformities
29
What may radiographs show in osteomalacia?
pseudofractures aka Looser's zones
30
What is serum bone biochemistry like in osteomalacia?
low calcium, low phosphate, high ALP
31
Treatment of osteomalacia?
vit D therapy with calcium and phosphate supplements
32
What is primary hyperparathyroidism due to?
benign adenoma, hyperplasia or perhaps malignant neoplasia
33
What does overproduction of PTH lead to?
hypercalcaemia
34
Symptoms and signs of hypercalcaemia?
fatigue, nausea, depression, polyuria, renal stones, osteoporosis etc etc
35
In hyperparathyroidism what happens to phosphate?
is normal or low
36
What is secondary hyperparathyroidism?
overproduction of PTH secondary to hypocalcaemia caused by vitamin D deficiency OR CKD
37
What is tertiary hyperparathyroidism?
patients with secondary hyperparathyroidism who develop an adenoma which will continue to produce PTH, usually CKD related