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Old 04-25-2011
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Bones Parathyroid Hormone; Is it good or bad for bones!

In parathyroid adenoma, there is an INCREASE in PTH levels leading to resorption of Ca in bones

; whereas in bone fractures we adminster PTH to increase the formation of bones

Both statements are supposedly true, however contradicting..what am i missing?
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Old 04-25-2011
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Both statements are correct my friend, however, in the second statement, it is worth note to add the word 'pulsatile PTH' ie not continuous administration - in that way we inhibit bone resorption - that is why it is used for osteoporosis!
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Old 04-26-2011
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Default Pulsatile or Continous

Similar concept applies to the treatment of Osteoporosis...

Teriparatide is a recombinant PTH which is scheduled qD so as to provide pulsatile exposure to PTH causing bone mineralisation

Teriparatide is the only form of treatment which can reverse osteoporosis to some extent, other treatments can only prevent further progression
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Old 04-26-2011
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Idea! mechanism

Quote:
Originally Posted by add1 View Post
Both statements are correct my friend, however, in the second statement, it is worth note to add the word 'pulsatile PTH' ie not continuous administration - in that way we inhibit bone resorption - that is why it is used for osteoporosis!
thnks for the useful answer..i want to know if someone can explain how the pulsatile PTH causes bone mineralisation n not resorption which is what it does normally in the body ..thnks
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Old 04-27-2011
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Idea! ?

i remember reading in kaplan physio that the PTH has rapid and long term actions. The rapid actions include increasing Ca reabsorption from the distal segment and decrease in phosphate re absorption at the proximal segment. Some of the other effects included increase Vit D from the PCT which leads to increase intestinal absorption of Ca and Ph (though i think that was also long term). going by this logic all these things would probably be helpful in bone mineralization? and there was a line about how long term PTH would decrease the solubility product due to increasing ca and decreasing Ph and hence case bone resorption. So in pulses is it that the PTH increases serum Ca by the rapid action and that is how it contributes to bone mineralization? Now I'm confused...
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Old 04-27-2011
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Post one way of looking at it

one way of looking at it is ...
pth enhances the release of calcium from its large reservoiur the bones.bone resorption is an indirect action of pth since pht do not directly stimulate osteoclast.rather pth bind to the osteoblast which then stimulate the intermediate protein that in turen stimulates the osteoclast this protein is the RANKL.these osteoclasts once stimulated help in resorption of bone and increasing the serum calcium level.so pulsatile release of pth might just be enough to stimulate the osteoblasts and not in enough quantity to stimulate the osteoclasts.also in the body under normal circumstances the pth is released in pulsatile manner n so there is a balance in the bone resoprtion and mineralisation with the balance being tipped more in favour of mineralisation than resorption .maybe(just a hunch)cont pth would cause more resorption n so not given .
please correct me if there is an error
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Old 04-30-2011
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You're right, lookingup.
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