biochemical disorders of bone Flashcards
what is osteomalacia/ Rickett’s
lack of mineralisation of osteoid (immature bone) resulting in abnormally soft bone (ricketts in children)
what causes osteomalacia (5)
insufficient calcium absorption, insufficient Vit D absorption/ production, post-menopause, phosphate deficiency, long term-anticonvulsants
what causes insufficient calcium absorption (osteomalacia)
lack of diet, defective absorption in GI tract
what causes insufficient vit D absorption (osteomalacia)
lack of sunlight/ vit D from diet (GI causes) causing secondary hyperparathyroidism (most common cause)
how does post menopause causes osteomalacia
lack of oestrogen
what causes can cause phosphate deficiency (osteomalacia)
renal disease, alcohol abuse
what are the symptoms of osteomalacia (4)
bone pain (pelvis, spine, femur), deformity (bowed legs, square head, pigeon chest), easily fractures, hypocalcaemia (cramp, fatigue, seizures)
what investigations can be done for ostoemalacia
X ray, biochem: low ca, low Vit D, low phosphate, high ALP and PTH
how do you treat osteomalacia
vit D replacement (Ca and phosphate supplements)
what is osteoporosis
decreased bone mineral density leading to increased risk of fracture with little trauma
what is the bone density of osteoporosis vs osteopenia
osteoporosis bone density 2.5SD below mean, osteopenia is intermediate stage and 1-2.4 SD below mean
what causes osteoporosis (6)
idiopathic, hyperparathyroidism, steroids, post menopause (loss of oestrogen and increased osteoclasts), old age, genes
what is type 1 osteoporosis
post menopausal –> increased osteoclast activity
what are risk factors for osteoporosis
smoking, white, alcohol, post menopause, sedentary, bad diet, vit D deficiency
what is type 2 osteoporosis
in elderly with greater density decline than normal
where do fractures usually occur in type 2 osteoporosis
femoral neck and vertebra
what are secondary causes of type 2 osteoporosis
endocrine (cushings and hyperparathyroidism), GI (malnutrition), drugs and alcohol (corticosteroids)
how do you diagnose osteoporosis
DEXA bone scan (gold standard), serum Ca and phosphate
what lifestyle measures can be used in osteoporosis management
exercise, increased Vit D in diet, sunlight
outline osteoporosis treatment
non curative, just slow progress. bisposphates –> desunomab –> stromium ranelate –> hormone replacement therapy (post menopausal women) (zolendronic acid)
what are bisphosphonates
reduce osteoclast activity eg alendronate
what is desunomab
monoclonal antibody that reduces osteoclasts
what is the use of zoledronic acid in osteoporosis
reduces fracture risk
what is hyperparathyroidism
too much PTH resulting in decreased calcium and phosphate in the bone by increasing osteoclasts