My EGFR last year was 57 and this year is 56. I asked my PCP for a referral to a nephrologist and he asked why I was making this request to I pointed this out to him. He said I don't have a kidney problem and my kidneys are in excellent health. My other lab work is within range but based on everything I've read this would classify me as having CKD stage 3. Should I trust what he's telling me or consult another doctor?