Ca & renal failure??

[MyEBee]

Why is it typical in renal failure for the Ca levels to be low but not any other electrolytes?? I can't seem to find anywhere how they are related, I know the tubules absorb and reabsorb, but I just don't understand why Ca would be low. Help please!!!??

[agoodusername]

Crap, I just had a test about this last week...so here goes. :)

In the body, Calcium levels and phosphate levels are inveresly related, so when calcium is high, phos is low, etc. etc. In renal failure, the kidneys lose the ability to excrete phosphate, so it kind of hangs out and accumulates. Calcium sees this, and therefore uses itself to metabolize phos/get rid of excess phos. In doing so, calcium levels are depleted. Adding to the problem is the fact that Vitamin D (which promotes Calcium uptake) is activated in the kidneys -- if the kidneys aren't working...no Vitamin D, no Calcium, bad news. The body senses this and begins to break down the bones in order to raise serum calcium levels. This leads to really frail renal failure patients -- lots of bone damage with very little trauma, and increasingly and chronically low calcium levels. Treatment is usually through a pill like Phos-lo, which binds to phosphorus and gets rid of some of it so that the relationship can be restored (low phos=high ca)

This is a really simplistic explanation which I just totally drew from my recent test-studying (yay! It actually worked!). A simple google search brought up this website, though...which will give you a much more detailed and scientific explanation of the issue.

UK NKF - Bones, Calcium, Phosphate, and PTH*in Kidney Failure

Isn't it interesting? The kidney is mad-complex...so fascinating!! Good luck!

[MyEBee]

thanks!!! that explains it perfectly :) I hope you did good on your test, it sounds like you should have!