I’m 82, recent GFR was 58. Same as about last 15 years. This was a fasting serum test. My eGFR does fluctuate. If I haven’t fasted, am eating sugar, etc., my serum GFR fluctuates, too.

We also have to remember that the formulae for eGFR uses age as a variable. So, no matter how good your other numbers for the formulae are, your age variable keeps your result low. It doesn’t really mean your kidneys are in danger. I tried once substituting a much younger age for the formulae, and I had to preteen I was about 30 to get a number 60 or above. This issue has been debated for a long time. Basically, if you are past a certain age, your eGFR forces a low number result. That’s been my experience.