Living Long-Term at Stage 4 Kidney Disease

@gingerw @siosal Mirror mirror on the wall, what is the best kidney function test of them all? There is a 24 hour urine test which tests for kidney function that many nephrologists use.

The two common eGFR tests are Creatinine which looks at muscle mass for kidney function and Cystatin C which looks at the "cells" in your body to give a value of kidney function. The differences of the two as I am told by nephrologists is that the eGfR creatinine test can fluctuate which is why you may see different values over time. I am also told that this test is about 65% accurate for kidney function. It is popular with nephrologists, endocrinologists, and PCPs because nearly all are covered by insurance. The lab test for Cystatin C, on the other hand, may not be covered by your insurance company. Most nephrologists use this as it is more definitive in accuracy (about 95%) and quite stable. The eGFR calculation of Cystatin C is determined by age so the lab test is different from the creatinine eGFR. It is quite possible that you can be in Stage 3 of kidney function by using the creatinine eGFR method and Stage 4 of Cystatin C eGFR at the same time. Most nephrologists care deeply about Cystatin C results.

Not talked about on this forum for over 4 or 5 years is the Iothalamate Study, which is unique to Mayo Clinic and other advanced hospitals. It is perhaps one of the best methods of study that uses nuclear medicine and eGFR to determine the function of each kidney. Without going into tons of detail about this method, your nephrologist will review the data and discuss the results with you and provide further treatment. This is perhaps the most definitive treatment for kidney function tests in my opinion.

Thank you @gingerw for your answers and showing the importance of kidney function testing.

I appreciate this response. My c cystatin test GFR was 35. Taken at the same blood draw, my creatinine GFR result was 27. That may not seem a big difference, but it puts me in 3rd stage rather than 4th stage which means a lot to me.

It seems more often c cystatin results are lower than creatinine. Is this the case?

@gingerw @siosal Mirror mirror on the wall, what is the best kidney function test of them all? There is a 24 hour urine test which tests for kidney function that many nephrologists use.

The two common eGFR tests are Creatinine which looks at muscle mass for kidney function and Cystatin C which looks at the "cells" in your body to give a value of kidney function. The differences of the two as I am told by nephrologists is that the eGfR creatinine test can fluctuate which is why you may see different values over time. I am also told that this test is about 65% accurate for kidney function. It is popular with nephrologists, endocrinologists, and PCPs because nearly all are covered by insurance. The lab test for Cystatin C, on the other hand, may not be covered by your insurance company. Most nephrologists use this as it is more definitive in accuracy (about 95%) and quite stable. The eGFR calculation of Cystatin C is determined by age so the lab test is different from the creatinine eGFR. It is quite possible that you can be in Stage 3 of kidney function by using the creatinine eGFR method and Stage 4 of Cystatin C eGFR at the same time. Most nephrologists care deeply about Cystatin C results.

Not talked about on this forum for over 4 or 5 years is the Iothalamate Study, which is unique to Mayo Clinic and other advanced hospitals. It is perhaps one of the best methods of study that uses nuclear medicine and eGFR to determine the function of each kidney. Without going into tons of detail about this method, your nephrologist will review the data and discuss the results with you and provide further treatment. This is perhaps the most definitive treatment for kidney function tests in my opinion.

Thank you @gingerw for your answers and showing the importance of kidney function testing.

@collegeprof A couple of years ago, I had a "split kidney function" test, that included a complicated examination and dye injection. It all had to be cleared by my nephrologist and oncologist beforehand. Measuring to see how each kidney was functioning, it revealed both were about the same. And due to my current brain fog, I cannot recall the reason for the test...

I have only had the creatinine eGFR testing done. But anything that will give us consistent and accurate results is tops in my book! We as patients should remember our hydration, diets, activity level, and even where the labs tests are run, in watching the trends for our kidney function.
Ginger

@gingerw The only test that I am aware of is the Iothalimate Study which is nuclear in nature and injected in the muscle of your upper arm. It is radioactive material like a dye called "radiotracer" and excreted into the urine by globular filtration. Again, the object is to test each kidneys function or "split kidney" function as you call it.

Cystatin C tests should be the gold standard for determining kidney function. I’ve had several major surgeries and “gold standard” was always used by medical professionals. I would think gold standard for who? Patients panic when they see fluctuations in creatinine kidney function. I did. I’d think did I drink enough water, exercise too much that made my muscles excrete creatinine, did I stress the kidneys from something or other? That’s not how it works. Yes, eat wisely, exercise, drink water. Ok. But to hang your emotions on every time you get a blood draw? Find the stability. C Cystatin seems to provide stability.