Effects of creatine supplementation on renal function: a randomized, double-blind, placebo-controlled clinical trial.
Level 2 - randomized trial
Individual randomized, double-blind, placebo-controlled trial
PubMed 18188581 · doi:10.1007/s00421-007-0669-3
What was done
Eighteen healthy sedentary males aged 18–35 years participating in a 3-month moderate-intensity aerobic training program (three 40-minute sessions per week) were randomized in a double-blind fashion to receive either creatine (~10 g/day) or a dextrose placebo. Serum creatinine, serum and urinary sodium, and potassium were measured at baseline and study end. Cystatin C was measured at baseline (PRE), 4 weeks (POST 4), and 12 weeks (POST 12).
What was found
Cystatin C significantly decreased over time in both groups (PRE creatine: 0.82 ± 0.09 mg/L; placebo: 0.88 ± 0.07 mg/L vs. POST 12 creatine: 0.71 ± 0.06 mg/L; placebo: 0.75 ± 0.09 mg/L; P = 0.0001), indicating an increase in glomerular filtration rate. Serum creatinine decreased with training in the placebo group but was unchanged in the creatine group. No significant differences were observed within or between groups for any other measured parameters.
Why it matters
It demonstrates that medium-term, higher-dose creatine supplementation does not induce renal dysfunction in healthy young men initiating aerobic exercise, supporting its renal safety profile in healthy populations.
Limits
The sample size is very small (n = 18). The study included only young, healthy, previously sedentary males, meaning results cannot be generalized to females, older individuals, or those with underlying kidney disease.
Cited by
- supports Creatine supplementation converts to creatinine and can falsely suggest kidney failure on standard blood tests, whereas cystatin C testing avoids this artifact.