GFR?

[JAYCEE33]

Is GFR calculated solely from the creatinine figure? I'm a 73 year old white male and my last creatinine result had increased to 148 with GFR at 40 - but all my other blood results in my renal profile are absolutely spot on - bang in the middle of normal range and always have been since taking monthly samples every 2 months. For the last 12 months the creatinine figure has varied between 129 and 148.

[Marvin8]

What you are referring to is eGFR or "estimated" GFR. The way to get the best reading of true GFR is to check your filtration rate directly, which is expensive, time consuming, and tedious. That's why doctors usually measure your serum creatinine. The other, and sometimes more accurate method, is to measure you Cystatin-C. Read some of my posts on the subject here and you'll see why it's usually a smart idea to demand that it be tested. Formulas that use a combination of both creatinine and Cystatin-C are generally considered the most accurate....even when compared to a direct measurement.

[JAYCEE33 in reply to Marvin8]

I have my Cystatin-C result for one of the renal blood tests about 3 months ago, what formula do I use?

[Marvin8 in reply to JAYCEE33]

Have fun.

kidney.org/professionals/kd...

[JAYCEE33 in reply to Marvin8]

I was mistaken, the test was for Serum C reactive protein! If my GP won't test for cystatin-C can I have the test done privately?

[Marvin8 in reply to JAYCEE33]

CRP is for inflammation.

Simply say to your doctor "I want my Cystatin-C tested!" ....period.

Tell him that when combined with creatinine, it's a better predictor. If you hold your ground, they'll test it. It's not an expensive test and it's good as a verifier to creatinine. If Cystatin-C eGFR is higher than Creatinine eGFR, that's a good thing. If it's lower, that's a bad thing.

[RickHow]

The eGFR has basically two commonly used formula's to calculate. One considers your age, your race, your sex, your creatinine level, and produces an egfr. The other takes into consideration the same facts but also includes your actual height and weight. Generally speaking the second method produces a higher egfr than the first. The first does not consider you actual height and weight but instead just uses what is "typical" for a person of you age, etc. Here is a link to a calculator where you can enter your information and get your egfr. You can use either method (using height and weight, or not).

[JAYCEE33 in reply to RickHow]

Hi Rick, there was no link? John

[RickHow in reply to JAYCEE33]

oops! here : kidney.org/professionals/kd...