The effect of creatine supplementation on kidney function: a systematic review and meta-analysis of randomized controlled trials.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 42035842 · doi:10.1053/j.jrn.2026.04.010
What was done
A systematic literature search was conducted to identify randomized controlled trials (RCTs) assessing the effects of creatine supplementation on kidney function. The primary outcomes analyzed by random-effects meta-analysis were serum creatinine, serum urea, and estimated glomerular filtration rate (eGFR). Subgroup analyses evaluated supplementation duration (<1 month vs. >1 month) and participant physical status.
What was found
A total of 19 RCTs and 1 double-blind randomized crossover study were included. Creatine supplementation was associated with a significant increase in serum creatinine (MD = 0.13 mg/dL, 95% CI: 0.07 to 0.18, n=19). There was no significant difference in serum urea concentrations (MD = -0.60 mg/dL, 95% CI: -2.15 to 0.96, n=12) or eGFR (MD = -5.20 mL/min/1.73 m², 95% CI: -15.00 to 4.60, n=8). No significant differences were observed between <1-month and >1-month supplementation subgroups for creatinine (p = 0.15), urea (p = 0.15), or eGFR (p = 0.88).
Why it matters
This review helps clarify that small increases in serum creatinine from creatine supplementation occur without measurable changes in urea or eGFR, suggesting the rise may reflect creatine metabolism rather than kidney damage.
Limits
Total participant count and specific baseline clinical characteristics are not reported in the abstract. Only 8 studies measured eGFR, resulting in wide confidence intervals, and no included studies evaluated outcomes beyond one year.