correlation between creatinine and eGFR

My eGFR jumps around between 36 and 55. I have been told that it is affected by other factors besides creatinine including changes in muscle mass. My nephrologist also uses the Cystatin C eGFR which is more stable.

I always learn a lot when someone poses a question because I go look for research.
Looks like creatinine often doesn’t rise much at the beginning of a change in kidney function. So you may have caught it early. Or possibly your muscle mass has remained high (increased lately?) that would keep creatinine high. I’m certainly no expert, and only looking through research as I also have had changes in scores lately.
For people with diabetes 2, a drop in eGFR of 7.6% looks significant. So much depends on where your health is now, including weight and diet changes.

Here’s the articles I was reading. You may already have this info, but I thought I’d send it along.

Medscape sometimes requires a log in to access, but this looks like it’s open to the public, about creatinine:
https://emedicine.medscape.com/article/2054342-overview#a1
False Estimates of Creatinine Levels
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3383162/
About the prognosis of renal disease based on annual eGFR rate drops (in diabetics)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5743850/
Sorry I couldn’t be more helpful!

@raj9 Welcome to Mayo Clinic Connect. You have had a couple great responses already. While you don't mention if you're dealing with other health issues at the same time, there are a few factors to consider. Your eGFR can be different from other test dates based on your hydration level, exercise, diet, stress, and even if the same testing site used different labs/machines to process the sample.

As you read through the posts here in the Kidney and Bladder Support Group, you will often see the statement we want to look at trends, not necessarily a single lab result. I know that is difficult to do, thought. Am I right?

How long was the time between these two tests you mentioned? Have you had any significant health concerns come to light recently?
Ginger

Thank you for those links! This one just gave me an insight as to why my creatinine levels are high, possibly. I intermittent fast! I have for years. This link suggests fasting can cause a rise in creatinine levels. My C Cystatin blood test results recently gave me a healthier result and put me in 3rd stage rather than 4th. The article suggests creatinine tests are false levels of creatinine. Now I wonder if intermittent fasting damages kidney function or if it's a false indication of kidney getting worse.
False Estimates of Creatinine Levels
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3383162/

Just search the Internet for eGFR calculator and you will get plenty of information about how the eGFR is calculated. Did you have a recent birthday? eGFR calculators factor in your age. The amount that your GFR changed may look large, but it's actually not all that significant an amount.

Carole@learn
Don't know what I'm doing, first time. Just found out I have Stg 3b CKD about 2-3 no ago. I'm 76 and found out by reading & studying my 'my charts' back about 6 yrs looking up what I didn't understand. No Dr, hosp, or nurse ever told me I had cod so I've spent the last two months finding a Spec. I need all the help I can get because my drs/ nurses response is one visit to a dietitian (if I wanted) 2 visits to my Dr and appts to Np to tell me I was close to end stage and my options for dialysis because I an 3b ckd. She said "Its good to plan ahead." I just finished reading about creating unique diets to try & help people with ckd esp in advanced stages. If I put this in the wrong place please forgive me. I just need all of your HELP. Thank you & Bless you.

You could try to get a Cystatin C e GFR to see if it is better than the creatinine based eGFR. Creatinine is affected by many factors that do not affect the Cystatin C. Hydrating well before blood tests like the creatinine eGFR may raise your result. Do you drink enough water? (I personally have a lot of trouble with hydration and no longer feel thirst very often.) I am close to 3b but my Cystatin C is much better.