@mimi1234 Welcome to Mayo Clinic Connect! You’ve come to the right place. Folks here are caring and sharing. Most have a lot of knowledge and experience to share.
Here’s my 2 cents worth.
Regardless of the lab tests used it is the trend over time that is important.
Lots of things affect kidney function (hydration, diet, other conditions, fitness level, exercise…..). It sounds like you are aware of these things and are doing the best you can.
eGFR does lower as one ages. I guess this is normal.
A nephrologist is the best specialist to shed more light on this if you continue to be concerned. I would be concerned that your GP says one thing and his physician’s assistant said something else contradicting the doc. That alone makes a worthwhile case to see a nephrologist!
Many of us here would be happy to have your numbers. I am nearly 68 years old and my eGFR is currently in the low 30’s. It has bounced between 14 - 42 since 2016 when my nephrologist diagnosed me with stage 4 CKD.
Will you let us know what you decide to do? My hope for you is the best provider and treatment possible.