Cystatin C egfr - affected by exercising?

[Bubbs]

My creatinine usually gets really high for the days following exercise to the point my traditional EGFR goes from high 70s down to even 40s if I do it the days after an intense back or leg workout because of the creatinine elevation

I just ordered cystatin C since that apparently isn't affected by muscle mass (I'm 240, 19" arms much more muscle than a "normal" person and work out very intensely 4 x a week), is it safe to take the test without cutting back on my work outs?

Also is it affected by what you eat? One time I took a regular egfr test a couple of hours after hitting a Brazilian BBQ and eating several pounds of steak, the results were.. interesting. Luckily my old dr was fine with it.

 

[Nelson Vergel]

Hi Bubbs

Cystatin C is not affected by body weight, creatine supplements, exercise or diet.

Search result for: 'cystatin-c-blood-test'

www.discountedlabs.com

 

[Nelson Vergel]

Cystatin C versus Creatinine in Determining Risk Based on Kidney Function - PMC

Adding the measurement of cystatin C to that of serum creatinine to determine the estimated glomerular filtration rate (eGFR) improves accuracy, but the effect on detection, staging, and risk classification of chronic kidney disease across diverse ...

www.ncbi.nlm.nih.gov

 

[Nelson Vergel]

Search result for: 'kidney-function-panel-comprehensive'

www.discountedlabs.com

 

[Bubbs]

Thank you Nelson! I hope the test results are good, the roller coaster numbers from traditional creatinine testing has got me a little concerned

 

[Bubbs]

I'll post here as soon as I get the result

for context,

Xmas 2018 eGFR If Africn Am - 48 (worked out 1 day before, ate, dehydrated)

June 2019 eGFR If Africn Am - 84 (no exercise for a week pre test, fasted)

Xmas 2019 - 55 (ate a ton of meat before the test)

June 2020 - 68 (no exercise for 3 days prior, ate cheeseburger that morning)

My other numbers are all fine but this and BUN to a degree seem to go up and down depending on my routine so it's really hard to see if I'm ok or not lol

 

[Bubbs]

Bump because I never updated this

My current TRT blood work has me at

Traditional eGFR = 58

Cystatin C = 0.73

eGFR calculated from Cystatin C = 116



That's a pretty huge difference!!

( using CKD-EPI Equations for Glomerular Filtration Rate (GFR) - MDCalc )

 

[Nelson Vergel]

Yes, it's pretty amazing for guys who work out and/or have a lot of muscle. Those taking creatine also see a huge difference.

 

[Bubbs]

Yes, it's pretty amazing for guys who work out and/or have a lot of muscle. Those taking creatine also see a huge difference.

For 10 years I've been told several times by various doctors that my kidneys are failing so it was nice to finally have proof that I'm fine!

This means it's safe to keep using my lisinopril with hczt I guess? One dr told me I needed to stop using that because of my "kidney damage" and he had me stop using celebrex for my joint pain. Damn.

Nelson is it worth using the combined cystatin c and creatinine calculation? I'm thinking no, but even if I do I'm still in the 90s.

 

[Nelson Vergel]

It amazes me how some doctors do not know even basic medicine 101.

Yes, cystatin-based eGFR is the most accurate method.

Why is your creatinine so high, though? Besides working out and protein intake, are you on any supplements? Why not run your CMP in a fasted state?

 

[Bubbs]

It could be because I injected 100mg the day before and had worked out intensely a couple of days before?

To clarify "so high" is 1.4 to 1.5 max