I take creatine supplement, and I’ve noticed that my creatinine levels are a little elevated, but when I discontinue the creatine a week or so before labs, creatinine levels are normal.
For a recent blood test, I forgot to d/c the creatine, so creatinine was elevated 1.7 mg/dL (ref range 0.5 - 1.3). GFR levels were also low:
eGFR AA: 48 mL/min/1.73 m2 (ref range >60 mL/min)
eGFR non-AA: 39 mL/min/1.73 m2 (ref >60)
These levels have previously been normal (above 60), but also occasionally low (43, 47, 58) – since 2018.
I recently switched to a new PCP, and he is concerned about the low GFR levels. My question: Since taking creatine supplement can elevate creatinine levels (and give a false positive for kidney dysfunction), can creatine supplement also cause low GFR levels?
I suppose the best test would be to d/c the creatine for a couple of weeks and then have labs run for all these levels. Meantime, I’m just wondering how eGFR levels are calculated – whether they can be altered by creatine the way creatine alters creatinine.
[Footnote: My previous PCP since 2013 was very thorough, and he was never concerned when GFR levels were low. He did once express some concern when creatinine levels were elevated. I told him I thought the creatine was the culprit, and subsequent labs seemed to confirm this: Without the supplement, creatinine levels returned to normal. That MD retired, and my new MD is concerned about low GFR in previous years. So, secondary question: How reliable are GFR levels as indications of kidney disease?]