Bone and Mineral Health Flashcards
the site of new bone growth?
epiphyseal plate
function fo osteoblasts
build bone
function of osteoclasts
break down bone
as we age what happens to our bone mass?
after the ages of 35-60 we lose 0.5-1% of bone per year
Why is Ca2+ necessary?
for muscle contraction(heart), for cell signaling, bone support
Where do we get Ca2+ from?
diet and bone
what happens if the plasma doesn’t have enough Ca2+ in it?
it will absorb from bone
what is necessary for bone absorption?
Vitamin D
What are the forms of vitamine D, what is the one usually refereed to?
D2 - dietary vitamin D
D3 - sunlight vitamin D
D3
what process do the kidneys aid in?
converting calcifediol to calcitrol
what happens in kidney failure?
we need to take calcitrol as body can’t do the conversion itself
what are the 3 means that vitamin D increases plasma Ca2+
- mobilixing from bone
- reabsoprtion by kidnerys (less excreted in urine)
- absorption from intestines (through diet and supllments)
what does PTH do?
allow for the creation of calcitriol in the kidenys
- mobilization from bone
- promotes reabsorption from the kidneys
- stimulates ysnthesis of calcitriol
How do vitamin D and PTH interact?
a negative feedback loop in order to prevent too much blood in the bone
what is the role of calcitonin?
the opppsoite
decrease plasma calcium, decrease reabsorption in kidneys
what is osteoporposis?
when bone reabsorption exceed depoistion
so the osteoclasts break down bone and mobilize calcium to plasma
leading to low mineral density - and increasing fracture risk
what are some risk factors for osteoporosis?
older age, inadequate calcium intake, genetics, smoking, hormones
what is the role of estrogen and osteoporosis?
estrogen is a protective factor
what are some other diseases of bone growth and calcium metabolism?
Rickets
osteomalacia
Paget’s disease
hypoparathyroidism and hyperparathyroidism
what hormones negatively effect bone growth? what’s happening?
Glucocorticosteroids (prednisone) - weaker bones
- decrease calcium absorption, thus increasing PTH
- decreased calcium absorption in kidneys
- decreased osteoblast activity
- increased osteoclast activity
what hormone positively impacts bone growth? how?
gonadal steroids (testosterone) - stronger bones
- decreased osteoclast activity, increasing osteoclast apoptosis, decreased osteoblast apoptosis
What are the three kinds of calcium supplements?
Calcium gluconate (IV), calcium carbonate (PO), calcium citrate (PO)
what are calcium supplements used to treat?
osteoporosis, hypoparathyroidism, elctrolyte imbalances
what is the MOA of calcium supllments?
increase bone and minaeral density/ strenth
what are the SE of calcium supp?
GI disturbances (carbonte cause more constipation then citrate), kidney stones
what is impoartnte to know about doisng calcium supp?
only 500 mg of elemntal calcium can be absorbed at once (so per dose)
what are vitamin D supps used to treat?
osteoporosis, hypoparathyroidism, rickets/osteomalacia
what is a common vit D supp that requires a prescription?
calcitriol ( reserved for those in kidney failure)
what is the MOA of vit D supps?
they increase intestinal calcium absorption
what are the SE of vit D supps?
usually none can cause hypercalcemia
What is the main drug class used to treat osteoporosis?
bisphosphates
MOA of bisphosphates
they inhibit the mevalonate pathway whihc leads to osteoclast apoptosis
what are typical and extreme side effects of bisphosphates?
nausea, vomiting, diarrhea, esophageal erosion
atypical femoral fracture, osteonecrosis of the jaw
in femal patienst what drugs can be used for osteoporosis trement?
hormone replacement therapy (HRT) (estrogen + progesterone)
selective estrogen receptor partial agonist/antagonist (raloxifene)
how does homone replacment therapy work/MOA and it’s side effects
MOA - increase osteoclast apoptosis and increase osteoblasts lifespan
side effects - increase risk of breat cancer, increased cardiovascular risk, breat tenderness, uterine bledding, venous thrombosis
how does selective estrogen receptor modulators (SERMs) therapy work/MOA and it’s side effects
MOA- estrogen partial agonist and antagonist
agonist in bone and CV tissue
anatagonist in mammaliary tissue and uterine tissue. thus combats cancer risk
increase sosteoclasts apoptosis and increase osteoblast activity
SE- hot flashes and venous thrombosis
Denusomab MOA and SE
MOA- a monoclonal antibody that binds RANKL and inhibits osteoclasts development and reduces their function/survival
SE - musculoskeletal pain, hypocalcemia, skin rxn
Teriparatide MOA and SE
PTH analog - injected once daily SC
MOA - promotes bone anabolism (forming new bone), by reducing osteoclast activity and increasing osteoblast activity
However, remember that PTH increases bone breakdown (catabolism)
so apparently intermittent exposure to PTH actually increases osteoblast activity and more then osteoclast thus one daily injection lead to bone growth
SE- hypotension, hypercalcemia, musculoskeletal pain
What is calcitonin used to treat?
osteoporosis, pagets and hypercalcemia
Calcitonin MOA and SE
calcitonin decreases bone reabsorption by decreasing osteoclast activity so there is less plasma Ca2+
SE- facial flushing, NVD
