Calcium homeostasis

[Lothric]

Hi,

First Aid says that increases in pH --> hypocalcemia as the affinity of albumin binding calcium ions increases. Costanzo, however, says that increases in pH --> less binding spots for calcium ions --> increased calcium ion concentration.

What do I believe?

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[FindMeOnTheLinks]

H+ competes with calcium for albumin binding. So a decreased pH will displace calcium from albumin and effectively cause a hypercalcemia. An increased pH will have the opposite effect.

Factors influencing the concentration of ionised calcium
http://www.tandfonline.com/doi/abs/10.3109/00365517209081058?journalCode=iclb20

 

[Lothric]

Wait, so what First Aid and Costanzo says is not a paradox after all?

In acidemia, the pH is increased --> more H+ binds the negatively charged spots on albumin, leaving fewer spots to calcium ions. This means that the free ionized calcium concentration should increase, no? That is literally what Costanzo says and it all makes sense to me, but apparently not.

I did not get any wiser from the links either

 

[FindMeOnTheLinks]

Wait, so what First Aid and Costanzo says is not a paradox after all?

In acidemia, the pH is increased --> more H+ binds the negatively charged spots on albumin, leaving fewer spots to calcium ions. This means that the free ionized calcium concentration should increase, no? That is literally what Costanzo says and it all makes sense to me, but apparently not.

I did not get any wiser from the links either

In acidemia the pH is decreased!

So yeah, in acidemia the pH is lower, there are more protons which displace calcium from albumin, more free ionized calcium. No paradox, you understand it but I think you just got confused about the directionality of pH changes.

 

[Lothric]

Wow, I can't believe I actually said what I said about acidemia and pH.

Thanks man, I got it now!