Calcitonin vs. Parathyroid Hormone

[Revilla]

I was under the impression calcitonin increased Ca and PTH decreased it, but my review book is exactly the opposite. Can someone verify that calcitonin decreases Ca while PTH increases it?

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[Andrew4010]

Calcitonin decreases the blood calcium level whereas PTH increases it.

 

[cwfergus]

Nope Calcitonin reduces Ca2+ concentrations, PTH will increase it

 

[iA-MD2013]

Calcitonin decreases the blood calcium level whereas PTH increases it.

Nope Calcitonin reduces Ca2+ concentrations, PTH will increase it

They are both correct

 

[supertrooper66]

I was under the impression calcitonin increased Ca and PTH decreased it, but my review book is exactly the opposite. Can someone verify that calcitonin decreases Ca while PTH increases it?

that's what my book says, too. calcitonin decreases blood Ca and PTH increases it. that's coming from kaplan.

i hate the hormones. not sure how many of them we really need to know. seems like the more obscure ones, like the ones you listed, would be included in a passage instead. ones like the catecholamines, aldosterone, and vasopressin i would assume you should know, though. no way I can prove that, tho!

 

[Revilla]

Thanks guys! I've had it backwards in my head this whole time.

 

[DrMattOglesby]

I always had trouble with these two hormones.
the things to remember are:

1. Parathyroid gets rid of Ca2+ from the bones and sends it to the bloodstream.
2. Calcitonin will tone up the bones by depositing Ca2+ from the bloodstream into the bones.

Alliteration is a fun game everyone can play!

 

[Revilla]

So that's where I was confused! Calcitonin increases Ca+2 in the bones by taking it from the bloodstream and Parathyroid increases Ca+2 in the blood stream by taking it from the bones.

 

[nityking]

you GOT IT! Since production of Estrogen/Progestrone decreases siginificantly in post-menopausal women, they cause increase osteoclast activity to increase blood calcium and decrease osteoblast activity (to form bones). Thus they are at high risk of suffering from osteoperosis than men! Now you would ask then why do they have to take regular Calcium pills if their blood Ca2+ will be technically higher? They are not higher cuz higher blood Ca2+ causes increase in its excretion by kidneys so they are still deficient of Ca2+ regardless of decrease in bone resorption.

 

[facetguy]

Calcitonin "puts the bone-in"! (i.e., puts the calcium INTO the bone). PTH does the opposite.

 

[DrMattOglesby]

lol
i love how everybody pretty much said the same thing in their reply to this thread <i'm guilty too>! As if more people saying the correct answer made it MORE accurate. Almost as if its correct by general consensus.

 

[facetguy]

lol
i love how everybody pretty much said the same thing in their reply to this thread <i'm guilty too>! As if more people saying the correct answer made it MORE accurate. Almost as if its correct by general consensus.

I learned that little mnemonic over 15 years ago and it continues to stick, so I thought I'd share it here.

 

[BloodySurgeon]

Also another idea to keep in mind would be to understand how other systems work with PTD and Calcitonin. Bone is made up of inorganic mineral hydroxyapatite that includes Calcium and Phosphates. So what happens to the phosphates after the calcium is removed? Where does the calcium and phosphates go? How does Vitamin D promote strong bones? How does calcium get to the bones from the blood? What is osteoclast vs. osteoblast? Osteocytes? If you can answer all these, then you will have a better understanding of how calicium homeostasis works. Search these on wikipeda and you will find your answers.

*hint* the small intestine and the kidneys play a role.

 

[nityking]

tricky question on AAMC: Bone formation involves not only the use of Ca and PO43- but also hydroxyl molecules combined with them two. There was a discrete question on it and guessed the wrong one OH- instead of Potassium, which doesn't not belong to bone matrix. Was thinking of hematopoetic stem cells in the bones and K+ is a major intracellular ion. Too much knowledge + over thinking = bad for MCAT

 

[Farcus]

remember this

When I think of calcitonin I think of something strong... if something is strong it needs a lot of Calcium in the bones, and thus a DECREASE in Ca2+ in bloodstream. I think of bloodstream as soft plushy weak sauce .

 

[zeevee]

in lack of weight bearing exercises how does serum calcium increase while PTH IS still low?

 

[momdozer]

I was under the impression calcitonin increased Ca and PTH decreased it, but my review book is exactly the opposite. Can someone verify that calcitonin decreases Ca while PTH increases it?

Calcitonin calcifies