Kidney Patient Guide

As part of my annual check for high blood pressure I have blood tests for liver, kidneys, etc. Last year the eGFR was 80, which, as I'm 74, I was very pleased about. This year the eGFR was 58, which caused some concern. I've just had my second blood test of three, to check for CKD, and this time the eGFR is 82. I'm, obviously, relieved, but totally baffled that there should be such a difference in tests. A few points I could understand, but 22? I've still got to have my third blood test and an ultrasound - I know I have numerous kidney stones - so am hoping that these turn out to be OK. At the time of the tests, I didn't have any infection, nor was I taking antibiotics. Both tests were in the morning after my usual breakfast and I'm pretty sure I wasn't dehydrated. Has anyone else had such a dramatic drop and rebound? Would kidney stones affect the result?

Hi Genevieve189,
Welcome to the forum.

eGFR is an estimate, and is notorious for its inaccuracy, it also sensitive to the amount you have eaten drunk that day.
It is best to consider trends rather than one reading on it's own.

Best wishes.

Thank you very much.

I was told some years ago that eGFR (the "e" is for "estimated") was only usefully accurate at low figures. If you have a "normal" kidney function (say above 50), eGFR can give some very unreliable results, so I wouldn't worry about it.

I think, before I donated a kidney some years ago, my eGFR was 75 or so, but my actual GFR (measured in a more complicated fashion) was 86 or thereabouts. As I recall, the estimated 75 figure was not good enough for me to donate!