@ditch4441 There are a myriad of reasons why a creatinine eGFR can go down, and not always solely one. It could be one to many. On your next trip to your nephrologist, ask your doc to look at the overall picture of all your labwork. If you go to a particular lab, see if they can give you a recap of the last year or multiple years to establish a eGFR trend. Lastly, many docs also use a Cystatin C test to check eGFR. However, some insurance companies do not cover this test which is why the creatinine eGFR test is more commonly used.