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Flashcards in osteoporosis Deck (85)
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1

Osteoporosis: Occurs when rate of bone _______ exceeds rate of bone _______

resorption
formation

2

what is the normal bone resorption process?

osteoclasts activation stimulated by RANKL

3

what is the activation of bone resorption in the pathologic process?

osteoclasts activation stimulated by PTH
(metastatic disease)

4

what is the process of bone formation? what are the 4 natural substances that promote this?

Inhibition of osteoclast, stimulation of osteoblasts
Osteoprotegerin (OPG)
calcitonin
estrogen
IL-10 inhibit osteoclast

5

what two main groups of natural substances regulate bone metabolism? what does is group include?

Hormones:
PTH, calcitonin, estrogen, androgens
Steroids:
Vitamin D, glucocorticoids

6

what do osteocytes do?

-formed after osteoblast activity
-release chemicals that say we need more osteroblast or clast activity (regulators)

7

what is OPG? (where does it come from and what does it do?)

released by osteocyte, it inhibits bone resorption by binding RANKL (holding it hostage so it cant activate osteoclasts)

8

what does RANKL do?

binds to RANK on osteoclast - activates the osteoclast

9

how does PTH exposure differ with release low intermittent vs high chronic?

low intermittent- bone formation (anabolic axn)
high chronic- bone resorption (breakdown) (catabolic axn)

10

how does PTH increase bone turnover?

PTH stimulate osteoblast to secrete IL-1, IL-6 and RANKL to activate osteoclast activity
RANKL binds to RANK proteins triggering the osteoclasts
Result is bone turnover and remodeling

11

PTH regulates what two substances? using what 3 organs?

Regulates calcium & phosphate using bone, kidney, and intestines

12

what does PTH do in the kidney?

Stimulates 1- α hydroxylase to convert calcidiol to calcitriol (to give active vitamin D - allows us to absorb Ca+ from intestine)
-tell kidney to keep Ca+ (DistalT) but get rid of phosphate (ProximalT)

13

what does PTH do in the intestine?

Indirectly increases intestinal calcium absorption by stimulation of 1,25 dihydroxyvitamin D production

14

Vitamin D: Increases serum ___and contributes to bone ______

calcium, mineralization

15

why is it so important to maintain Ca+ and phosphate balance? - (what if they get too high?)

need to maintain so they dont precipitate and accumulate in places like the lungs

16

what is the net effect of calcitonin?

Increase serum calcium -> calcitonin secretion -> inhibition of osteoclast -> decreased serum calcium

17

what is a hypocalcemic hormone that OPPOSES the effect of PTH?

calcitonin

18

estrogen's effect on osteocyte, blasts and clasts

- decrease osteocyte and osteoblasts apoptosis
-increase osteoclast apoptosis

19

what is estrogen good for in regards to bone health? why is this important?

Estrogen is better at preventing bone loss than building bone.
dont give post- menopausal women estrogen to increase bone density unless last resort (other agents are better)

20

glucocorticoid's effect on bones?

Antagonize vitamin D effect (decreasing intestinal calcium transport)
Blocks bone formation by inhibiting osteoblast activity
=overall : block bone formation

21

prolonged exposure to steroids can cause what effects in adults? children?

prolonged exposure to steroids can cause osteoporosis in adults and stunts skeletal development in children

22

what Can be useful at reversing hypercalcemia associated with lymphomas?

glucocorticoids

23

7 agents used to affect bone mineralization

Bisphosphonates
Human parathyroid hormone related peptide analogs
Monoclonal Antibody
Sclerostin Inhibitor
Conjugated Estrogens/SERMS
Calcitonin
Calcium
Vitamin D

24

Drug of choice (first line) for treatment of osteoporosis

bisphosphonates

25

what are the bisphosphonate drugs?

*Alendronate (Fosamax)
*Risedronate (Actonel, Atelvia)
Ibandronate (Boniva)
Zolendronic acid (Reclast)- IV formulation (once a year infusion)

26

only bisphosphonate that is not first line b/c no help for hip/nonvertebral fractures

ibandronate (boniva)

27

which bisphosphonate is IV formulation - (once a year infusion)

zolendronic acid

28

bisphosphonate MOA

bind Ca+ - taken into bone in high concentrations
they are taken up by osteoclast (and destroy the proteins that make their fringe border so they can’t chew up the bone)
= osteoclast apoptosis = decr rate of resorption

29

what is important to remember about the abs. of oral bisphosphonates?

When given orally little is absorbed – less than 1%
must take on empty stomach for max absorption

30

any metabolism for bisphosphonates?

no!