Step I question about Cinacalcet

[MudPhud20XX]

FA 15 on page 340, it says cinacalcet is used for hypercalcemia due to primary or secondary hyperparathyroidism. But don't you get hypocalcemia in the secondary hyperparathyroidism? It says cinacalcet sensitizes Ca2+ sensing receptor, so how is that going to work in hyperparathyroidism?
Many thanks in advance.

 

[allojay]

I'm not too sure about the answer since its been a while since I've covered it but from what I remember from my ENDO block, we were taught that It pretty much binds the Ca2+ sensing receptor instead of calcium. It's fights calcium for the CaSR. So as a result less PTH is being secreted. This means less calcium being made. The image below shows it clearly. Hopefully this clears it up.

http://image.slidesharecdn.com/pth-...hronic-renal-failure-47-728.jpg?cb=1225701375