@gladiator14 my nephrologist wants me to ingest more salt and protein. The causes of low GFR's or drops in GFR's based on creatinine can be complicated and can include low blood pressure (hence the salt) and muscle wasting (hence the protein). One size does not fit all. I had an echocardiogram to check heart function, which can also be a factor. I know I need to hydrate more too. The Cystatin C was necessary for me to see what was really going on with kidneys.

I am just saying, that a deeper investigation of drops in GFR can yield varying dietary protocols so don't assume you should limit salt and protein until your doc says so! I never do anything without understanding why.

ps My doc is a female! It is good to use the pronoun "they" when unsure of gender.