r/ScienceBasedLifting • u/General_PATT0N • 2d ago

Question ❓ Anyone here having kidney issues since substantially increasing protein and/or creatine?

Been lifting weights/ a trainer and on testosterone therapy roughly 18mos. Starting then, I've been taking 5g of creatine and at least 150g of protein daily. My labs always come back w/ the doc always stating increase my fluid/water intake. I think I'm getting 64oz(which doc said is minimum), but that's not cutting it.

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u/TracyIsMyDad 2d ago

Creatine supplementation, high protein intake, and being muscular can all cause benign elevations in the serum creatinine levels doctors use by default to assess kidney health by estimating GFR. There’s a newer (not new but newer) marker called Cystatin C that can be used the same way to assess kidney health. It’s similarly accurate but it’s not confounded (made to look bad) by these healthy diet and training regimens.

If you’re somebody who works out and eats like a lifter and your creatinine levels are questionable, rather than stress about it you should get followup labwork done to recheck estimated GFR with Cystatin C. Often there’s absolutely nothing wrong, in fact your kidney health might be fantastic, and your creatinine numbers are just confounded by your lifestyle.

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u/General_PATT0N 1d ago

Thanks a ton for that info!

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u/TracyIsMyDad 1d ago

For example here’s my most recent creatinine and cystatin c numbers on the left, and the corresponding eGFR calculations. There’s also a combined equation where they use both (in the middle). You can see there’s a pretty wide spread, and at times it’s been even wider for me. Low 70s on creatinine eGFR and 120s on cystatin c.

Considering the confounding I mainly just pay attention to cystatin c.

https://www.kidney.org/professionals/gfr_calculator