@rotate Both eGFR for creatinine muscle mass and Cystatin C eGFR for cellular involvement are estimated. When working with these 2 labs only, nephrologists first look at a trend of 6 months or longer to establish a "baseline". But there are other factors to consider such as sodium, pottasium, & phosphorous labs to work with these other 2 tests. There is a host of other things that I would suggest as well, and that involves an endocrinologist who should make sure your thyroid is normal by a TSH test and A1C diabetic test along with a cardiologist and his/her recomendations. For the type 2 diabetic, all of these are important to develop an ongoing strategy of living with kidney disease.

To set aside worries, the best way to determine true kidney function on each kidney is to take either an iothalamate or iohexol test. The former uses a catheter if urine stream is slow, and the latter is a simple blood test. At Mayo Phoenix, they only offer the iothalamate test. At Rochester. I believe they offer both. Many specialty and educational hospitals offer them.

The most important part of all of this is not to be distressed by one test. The creatinine eGFR may tend to do that while the Cystatin C is a liitle bit more stable. If you have normal sodium, potassium, & phosphorous levels, that is significant.

Last thing, make sure you are hydrated before any test. If you take labs early in the morning, drink enough water before the test. That may have been the problem of a lower than usual score.