When to be concerned about eGFR?

Don’t have a lot to share, but I had poor renal function looking like the beginning of ESRD, but it was because I had an obstruction with a stone. When it did pass it was resolved. I passed the stone on my own at home. As far as a PCP I know my last one took some getting used to. He later felt like great support and he left. I was so sad that he left. I live in a place where it is a long wait for a new one. I don’t have that. I would say to get on some wait lists if you do want one. Always trust your gut on things. Just because someone says he is good he might or might not be a good match for you. Only you were in the appointment and only you know best.

@sharlea1313 In my opinion, there is a difference between cautionary and insignificant. eGFR quite often jumps between values from day to day and perhaps within a day and among various labs. Cystatin C eGFR perhaps is more stable. A score of 53 out of normal 60 is still a good value so I agree with your doc, that at this point it is of no concern, but cautionary. eGFR works only with trends so if you are concerned, have the test repeated in 2 or 3 months. The "e" in eGFR means "estimated", so it is nothing more than that. The only true tests for kidney function are the iothalamate and/or iohexol, and you are nowhere near that. Stages 1, 2, and 3a are cautionary, easily handled by your PCP with repeat testing, and a referral to a nephrologist if your PCP deems nevessary.

@collegeprof I recently had my first Cystatin C eGFR and it was 38. Same day, and all previous times for months, creatinine eGFR has bounced around in the 50s.

I need meds that have some nephrotoxicity.

I’m confused.

@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.

@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.

@collegeprof Thanks for the detailed info. I sent a query just now to the endocrinologist who ordered Reclast for infusion 2 days from now, which has warnings about nephrotoxicity. We'll see what she thinks about the difference between the creeatinine eGFR and Cystatin eGFR.

So far, my PCP hasn't asked for a nephrology consult. We'll see.

@rotate The endocrinologist, among other things, is concerned about thyroid and blood sugar, not so much eGFR, as that responsibility is the nephrologist to help monitor that for you. High or low TSH values of your thyroid may affect eGFR. As previously stated., hydration is equally important as well as some contra-indicated medications. I personally would share your endocrinology lab work with your nephrologist so he/she is better informed about your kidney function. Last thing, if you have not seen a nephrologist yet, please do so. As I stated before, one lab value is not as important as a trend of values to establish a baseline. The value of 39 and your baseline require a nephrologist, not an endocrinologist. Your one value of 39 is just below average kidney function.

@collegeprof

Thanks for the info. I don't have a nephrologist - the endo ordered the infusion that is at issue.

My primary has not asked for a nephrologist to be involved. Maybe I should get a consult. All of this is within Mayo Clinic PHX so it's easy to do (but can take months to in to a specialist, even as a long established Mayo patient. But the endo is paying attention to the kidney issue, just not a specialist there. The reason for the referral was bone density danger from very low testosterone (prostate cancer post-radiation treatment).

My baseline on the creatinine eGFR has been steady. It was >60 until prostate cancer treatment, then it dropped to oscillating in the '50s. I have only had one of the Cystatin, done at my request - so no trend to look at.