GFR vs creatinine clearance vs serum creatinine

[mom2three]

I read the interesting information about the difference between GFR and creat clearance.. but isn't it effective enough to just monitor serum creatinine?  That's what my nephrologist seems to watch, and is certainly easier than collecting urine, less costly than the inulin method, and doesn't involve an approximate calculation. What's the downside of just watching that one number as a measure of kidney health post donation?

[WilliamLFreeman]

mom2three,

For monitoring change over time after donation, serum creatinine is fine.  There is little reason to do monitor eGFR or mGFR.  (Incidentally, almost all labs automatically report the eGFR -- most still by MDRD, some by CKD-EPI -- in the printout that reports the serum creatinine.)

The need for eGFR or mGFR occurs in 2 situations only:
   1]   when a person or doc wants to know in what "stage" of CKD the person is -- because the stages of chronic disease are defined by GFR, not serum creatinine; and
   2]   when a LKD or doc wants to know what was the change of kidney function [= GFR] from before-donation to after-donation -- because the change in serum creatinine is not sensitive or accurate enough to say something like "your post-donation kidney function is __% of your pre-donation kidney function."  (Kidney function does not change in a straight line of change in serum creatinine.)

So, your nephrologist is "right on."   

BTW, when I write "doc," I mean physicians, nurse practitioners, etc.   

Bill