biochemical disorders of bone Flashcards

1
Q

what is osteomalacia/ Rickett’s

A

lack of mineralisation of osteoid (immature bone) resulting in abnormally soft bone (ricketts in children)

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2
Q

what causes osteomalacia (5)

A

insufficient calcium absorption, insufficient Vit D absorption/ production, post-menopause, phosphate deficiency, long term-anticonvulsants

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3
Q

what causes insufficient calcium absorption (osteomalacia)

A

lack of diet, defective absorption in GI tract

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4
Q

what causes insufficient vit D absorption (osteomalacia)

A

lack of sunlight/ vit D from diet (GI causes) causing secondary hyperparathyroidism (most common cause)

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5
Q

how does post menopause causes osteomalacia

A

lack of oestrogen

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6
Q

what causes can cause phosphate deficiency (osteomalacia)

A

renal disease, alcohol abuse

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7
Q

what are the symptoms of osteomalacia (4)

A

bone pain (pelvis, spine, femur), deformity (bowed legs, square head, pigeon chest), easily fractures, hypocalcaemia (cramp, fatigue, seizures)

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8
Q

what investigations can be done for ostoemalacia

A

X ray, biochem: low ca, low Vit D, low phosphate, high ALP and PTH

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9
Q

how do you treat osteomalacia

A

vit D replacement (Ca and phosphate supplements)

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10
Q

what is osteoporosis

A

decreased bone mineral density leading to increased risk of fracture with little trauma

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11
Q

what is the bone density of osteoporosis vs osteopenia

A

osteoporosis bone density 2.5SD below mean, osteopenia is intermediate stage and 1-2.4 SD below mean

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12
Q

what causes osteoporosis (6)

A

idiopathic, hyperparathyroidism, steroids, post menopause (loss of oestrogen and increased osteoclasts), old age, genes

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13
Q

what is type 1 osteoporosis

A

post menopausal –> increased osteoclast activity

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14
Q

what are risk factors for osteoporosis

A

smoking, white, alcohol, post menopause, sedentary, bad diet, vit D deficiency

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15
Q

what is type 2 osteoporosis

A

in elderly with greater density decline than normal

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16
Q

where do fractures usually occur in type 2 osteoporosis

A

femoral neck and vertebra

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17
Q

what are secondary causes of type 2 osteoporosis

A

endocrine (cushings and hyperparathyroidism), GI (malnutrition), drugs and alcohol (corticosteroids)

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18
Q

how do you diagnose osteoporosis

A

DEXA bone scan (gold standard), serum Ca and phosphate

19
Q

what lifestyle measures can be used in osteoporosis management

A

exercise, increased Vit D in diet, sunlight

20
Q

outline osteoporosis treatment

A

non curative, just slow progress. bisposphates –> desunomab –> stromium ranelate –> hormone replacement therapy (post menopausal women) (zolendronic acid)

21
Q

what are bisphosphonates

A

reduce osteoclast activity eg alendronate

22
Q

what is desunomab

A

monoclonal antibody that reduces osteoclasts

23
Q

what is the use of zoledronic acid in osteoporosis

A

reduces fracture risk

24
Q

what is hyperparathyroidism

A

too much PTH resulting in decreased calcium and phosphate in the bone by increasing osteoclasts

25
what stimulates PTH production
low serum Ca
26
what hormone opposed PTH
calcitrol from thyroid increases Ca absorption to bone
27
what are the symptoms of hyperparathyroidism
hypercalcaemia: bones, stones, abdo groans and psychic moans. (thirst, polyuria, N+V, depression, fractures)
28
what causes primary hyperparathyroidism, what is the biochem, and how do you treat it
adenoma, hyperplasia of parathyroid. biochem: raised Ca, PTH and ALP, remove surgically
29
what causes secondary hyperparathyroidism, what is the biochem, and how do you treat it
CKD or Vit D deficiency. biochem: high PTH, Ca low/normal, treat underlying cause
30
what causes tertiary hyperparathyroidism, what is the biochem, and how do you treat it
overactivity from longterm secondary hyperparathyroidism. biochem: high Ca and PTH. parathyroidectomy
31
hyperparathyroid management
treat underlying causes, bisphosphonates, cinacalct (ca mimic), HRT, parathyroidectomy (end stage)
32
what is Pagets disease
altered bone remodelling --> increased osteoclastic activity and bone turnover
33
what does Pagets lead to in the bone
cortical thickening, brittle bone, weakened and misshapen, soft tissue swelling
34
what can cause Paget's disease
old age, metabolic disease, genetics, virus eg paramyxovirus
35
what are symptoms of Pagets
bone pain (pelvis, skull, spine, legs), arthritis and deformities, nerve compression, pathological fractures
36
how do you treat Pagets
bisphosphonates, joint replacement, (calcitonin)
37
what is avascular necrosis
bone infarction leading to necrosis of bone and bone marrow
38
how can AVN cause OA
patchy slcerosis --> subchondral collapse --> OA
39
what are common AVN sites
femoral head, humerus head, scaphoid
40
what can cause AVN
alcohol or steroid abuse, thrombus, sickle cell anaemia, SLE, secondary to fractures
41
how does alcohol and steroid abuse cause AVN
alters fat metabolism and promotes blood coagulation leading to compressed venous outflow
42
how to investigate and treat AVN
MRI>X ray, drill holes to decompress bones, joint replacement
43
which bone disease is qualitative
osteomalacia and rickett's
44
which bone disease is quantitative
osteoporosis