Creatine Supplementation and Creatinine

Medical Q&A [Moderated]
1

Hey Barbell Medicine,

I’m an avid lifter and current Second Year Medical Student (currently studying for step 1), and something that had me thinking was the topic of Creatinine values for AKI while individuals are supplementing with Creatine Monohydrate.

The backstory:
This came about while I was at my Drs for a check up and as my phyisician was looking at my CMP they noticed my creatinine was 1.4 (ref 1.28mg/dL) and my eGFR being 72. This wasn’t surprising to me since I supplement with Creatine monohydrate, Knowing that creatine is metabolized into creatinine and that creatinine is also used within eGFR calculations I figured it would be falsely elevated. My Dr was worried for AKI however I tried to explain how it may be falsely elevated and it wasn’t something I was really worried about. I don’t think my Dr understood the biochemistry behind why it may be elevated primarily because they didn’t understand why I was taking creatine in the first place lol. Not wanting to come off as trying to educate an attending, I left it at that.

However I it did leave me to wonder in cases of AKI or other Kidney pathologies that relay on creatinine and eGFR, how would an individual supplementing with creatine throw off those values and affect the management of those patients. Would this change in the Hospital/ Outpatient setting?

Thanks !
Rithin

2

Yep, I discussed this here:

Assessment of acute kidney injury in the hospital typically relies on creatinine measurements, but can also involve other things including urine output, electrolytes (in blood and urine), urinalysis, urine microscopy, and/or ultrasonography of the kidneys and bladder. If I were concerned about confounding from creatine supplementation I’d likely send a Cystatin C measurement, as described in the article above.

My creatinine was last measured at 1.4-1.5, however I requested a Cystatin C measurement which subsequently resulted at 0.7 mg/dL. There are now CKD-EPI equations using Cystatin C alone, or in combination with Creatinine, for eGFR estimation.

1 Like
3

Awesome! Thanks for the response. I’ll definitely read more into cystatin C!