biochemical disorders of bone

Question 1

what is osteomalacia/ Rickett’s

Answer 1

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

Question 2

what causes osteomalacia (5)

Answer 2

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

Question 3

what causes insufficient calcium absorption (osteomalacia)

Answer 3

lack of diet, defective absorption in GI tract

Question 4

what causes insufficient vit D absorption (osteomalacia)

Answer 4

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

Question 5

how does post menopause causes osteomalacia

Answer 5

lack of oestrogen

Question 6

what causes can cause phosphate deficiency (osteomalacia)

Answer 6

renal disease, alcohol abuse

Question 7

what are the symptoms of osteomalacia (4)

Answer 7

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

Question 8

what investigations can be done for ostoemalacia

Answer 8

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

Question 9

how do you treat osteomalacia

Answer 9

vit D replacement (Ca and phosphate supplements)

Question 10

what is osteoporosis

Answer 10

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

Question 11

what is the bone density of osteoporosis vs osteopenia

Answer 11

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

Question 12

what causes osteoporosis (6)

Answer 12

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

Question 13

what is type 1 osteoporosis

Answer 13

post menopausal –> increased osteoclast activity

Question 14

what are risk factors for osteoporosis

Answer 14

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

Question 15

what is type 2 osteoporosis

Answer 15

in elderly with greater density decline than normal

Question 16

where do fractures usually occur in type 2 osteoporosis

Answer 16

femoral neck and vertebra

Question 17

what are secondary causes of type 2 osteoporosis

Answer 17

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

Question 18

how do you diagnose osteoporosis

Answer 18

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

Question 19

what lifestyle measures can be used in osteoporosis management

Answer 19

exercise, increased Vit D in diet, sunlight

Question 20

outline osteoporosis treatment

Answer 20

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

Question 21

what are bisphosphonates

Answer 21

reduce osteoclast activity eg alendronate

Question 22

what is desunomab

Answer 22

monoclonal antibody that reduces osteoclasts

Question 23

what is the use of zoledronic acid in osteoporosis

Answer 23

reduces fracture risk

Question 24

what is hyperparathyroidism

Answer 24

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

Question 25

what stimulates PTH production

Answer 25

low serum Ca

Question 26

what hormone opposed PTH

Answer 26

calcitrol from thyroid increases Ca absorption to bone

Question 27

what are the symptoms of hyperparathyroidism

Answer 27

hypercalcaemia: bones, stones, abdo groans and psychic moans. (thirst, polyuria, N+V, depression, fractures)

Question 28

what causes primary hyperparathyroidism, what is the biochem, and how do you treat it

Answer 28

adenoma, hyperplasia of parathyroid. biochem: raised Ca, PTH and ALP, remove surgically

Question 29

what causes secondary hyperparathyroidism, what is the biochem, and how do you treat it

Answer 29

CKD or Vit D deficiency. biochem: high PTH, Ca low/normal, treat underlying cause

Question 30

what causes tertiary hyperparathyroidism, what is the biochem, and how do you treat it

Answer 30

overactivity from longterm secondary hyperparathyroidism. biochem: high Ca and PTH. parathyroidectomy

Question 31

hyperparathyroid management

Answer 31

treat underlying causes, bisphosphonates, cinacalct (ca mimic), HRT, parathyroidectomy (end stage)

Question 32

what is Pagets disease

Answer 32

altered bone remodelling –> increased osteoclastic activity and bone turnover

Question 33

what does Pagets lead to in the bone

Answer 33

cortical thickening, brittle bone, weakened and misshapen, soft tissue swelling

Question 34

what can cause Paget’s disease

Answer 34

old age, metabolic disease, genetics, virus eg paramyxovirus

Question 35

what are symptoms of Pagets

Answer 35

bone pain (pelvis, skull, spine, legs), arthritis and deformities, nerve compression, pathological fractures

Question 36

how do you treat Pagets

Answer 36

bisphosphonates, joint replacement, (calcitonin)

Question 37

what is avascular necrosis

Answer 37

bone infarction leading to necrosis of bone and bone marrow

Question 38

how can AVN cause OA

Answer 38

patchy slcerosis –> subchondral collapse –> OA

Question 39

what are common AVN sites

Answer 39

femoral head, humerus head, scaphoid

Question 40

what can cause AVN

Answer 40

alcohol or steroid abuse, thrombus, sickle cell anaemia, SLE, secondary to fractures

Question 41

how does alcohol and steroid abuse cause AVN

Answer 41

alters fat metabolism and promotes blood coagulation leading to compressed venous outflow

Question 42

how to investigate and treat AVN

Answer 42

MRI>X ray, drill holes to decompress bones, joint replacement

Question 43

which bone disease is qualitative

Answer 43

osteomalacia and rickett’s

Question 44

which bone disease is quantitative

Answer 44

osteoporosis