Best kidney markers for lifters

[full_silver]

My PCP is concerned that I have kidney issues and might develop renal insufficiency. My creatinine was 133 and eGFR was 63 (forgot the units for both but it's Canadian so I think it's SI units, the top limit for creatinine is 120 and GFR needs to be >=60). It is my understanding that individuals with more muscle mass and supplement creatine can have elevated creatinine so I'm wondering what the alternative would be to assess renal function. Thanks.

[Jordan Feigenbaum]

Full_silver,

I'm not sure what your actual numbers were and the units are definitely important, but I can understand that this can be a frustrating situation for you.

That said, there is no one perfect kidney marker for those with higher levels of muscle mass and/or who undergo rigorous training. Previously, a serum cystatin C, which is a protein produced by all cells containing a nucleus, was thought to be useful in this situation. However, subsequent data finds reduced precision and other biases that make this a poor choice in isolation. That said, combining a serum cystatin C (about 3-4 dollars USD) with a serum creatinine (about 1.50 USD) +/- a urine creatinine would be what I would do here, though other clinical contexts would change my opinion here.

-Jordan