Biochemistry Flashcards
What is osteoporosis?
reduced bone mineral and increased porosity
leads to bone fragility and increased fracture risk
what is the intermediate stage before osteoporosis?
osteopenia
why does loss of bone mineral start occuring at around 30?
due to gradual slow-down of osteoblast activity
why do females tend to lose more bone mineral density after menopause?
due to increased osteoclastic bone resorption
this occurs due to loss of protective effects of oestrogen
what are the two types of osteroporosis?
type 1: post-menopausal osteoporosis
type 2: osteoporosis of old age
what are the 8 additional risk factors to osteoporosis?
alcohol abuse smoking poor diet lack of exercise reduced sunlight exposure corticosteroid use malnutrition chronic disease endocrine disorders
what type of osteoporosis do colles fractures and vertebral insufficiency fractures usually occur in?
type 1 osteoporosis
what type of osteoporosis do femoral neck fractures and vertebral fractures usualy occur in?
thype 2 osteoporosis
how do you diagnose osteoporosis?
dexa bone scan
what are the main pharmacological treatments used to prevent further loss of bone density?
vitamin D and calcium supplements
biphosphonates
desunomab (a monoclonal antibody)
strontium
how does biphosphonate help prevent further loss of bone density?
reduce osteoclastic resorption
how does desunomab help prevent further loss of bone density?
reduces osteoclast activity
how does strontium help prevent further loss of bone density?
increases osteoblast replication
what are the pros and cons of Zoledronic acid? (a IV form of biphophonate)
pro- once yearly
con- more expensive than oral forms
when can HRT be used in the prevention of osteoporosis?
when side effects with preferred medications occur
what are the risks of HRT?
breast cancer
endometrial cancer
DVT
what is raloxifene?
an oestrogen receptor modulator which can be used in prevention of type 1 osteoporosis
what are the risks of raloxifene?
DVT
at present, what is the medication that has the greatest efficacy, cost-effectiveness and low side-effect profile in the prevention of osteoporosis?
biphophonates
What is osteomalacia (and Ricketts)?
abnormal softening of the bone due to deficient mineralisation of osteoid bone
why is there deficient mineralisation of osteoid bone in osteomalacia or ricketts?
occurs secondary to inadequate amounts of calcium and phophorus or vit D
compare serum calcium, phosphate and alk phosphate levels in a patient with osteoporosis and osteomalacia?
osteoporosis- serum levels normal
osteomalacia- low serum calcium, low serum phosphate, high alk phosphate
what is the treatment of osteomalacia?
vitamin D therapy
calcium and phosphate supplementation
what is hyperparathyroidism?
overactivity of the parathyroid glands causing high levels of PTH
what are the 3 causes of primary hyperparathyroidism?
benign adenoma
hyperplasia
malignant neoplasia (rare)
what are the serum levels of PTH, calcium and phorphate in primary hyperparathyroidism?
PTH is high
calcium is high
phosphate is normal or low
what is secondary hyperparathyroidism?
physiological overproduction of PTH secondary to hypocalcaemia
(hypocalcaemia usually caused by vit D deficiency or chronic kidney disease)
what is tertiary hyperparathyroidism?
when patients with chronic secondary hyperparathyroidism develop an adenoma which will continue to produce PTH despite biochemical correction
