Taking creatine, a common fitness supplement, slightly raises a blood test result called creatinine, which is a waste product that doctors use to check kidney health. The increase is very small—about 0.07 units—but it's a real difference seen when combining results from 12 studies.
See the scientific wording
According to a meta-analysis of 12 studies, creatine supplementation at standard doses (3-5 g/day) is associated with a small but statistically significant increase in serum creatinine levels compared to control, with a pooled mean difference of 0.07 µmol/L (95% CI: 0.01-0.12) among 177 creatine users and 263 controls.
Strong evidence
One moderate-quality study supports this claim, so treat this as an early signal rather than settled science.
What the research says
1 study reviewedSupporting (1)
Effect of creatine supplementation on kidney function: a systematic review and meta-analysis
Systematic Review With Meta-AnalysisMeta-analysis2025
The study looked at 12 experiments with creatine and found that people taking it had a tiny bit more creatinine in their blood, but their kidneys were still working fine, just like the claim says.
Contradicting (0)
No contradicting studies found yet
That doesn't mean it's settled — it just means no study has tested the opposite.
Quality-weighted scoring: we follow the GRADE framework — each study is rated High, Moderate, Low, or Very Low based on study design, methodology rigor, and risk of bias. A single high-quality RCT can outweigh several weaker observational studies.
Scores reflect study quality, not just count.
When a person takes creatine, their muscles store more creatine. The body turns extra creatine into a waste product called creatinine. This creatinine goes into the blood, so blood creatinine levels go up a little bit. But the kidneys still filter blood normally, so kidney function stays good.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting study
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Taking creatine, a common fitness supplement, slightly raises a blood test result called creatinine, which is a waste product that doctors use to check kidney health. The increase is very small—about 0.07 units—but it's a real difference seen when combining results from 12 studies.
Mechanism
1 studyTaking creatine makes muscles hold more creatine. The body changes extra creatine into creatinine, which goes into the blood. This makes blood creatinine go up a bit, but the kidneys work fine, so the rise is not from kidney problems.
When a person takes creatine, their muscles store more creatine. The body turns extra creatine into a waste product called creatinine. This creatinine goes into the blood, so blood creatinine levels go up a little bit. But the kidneys still filter blood normally, so kidney function stays good.
Oral creatine supplementation increases intramuscular creatine and phosphocreatine stores, expanding the body's creatine pool.
Excess creatine is non-enzymatically converted to creatinine, a metabolic byproduct, at a rate proportional to total creatine stores.
The increased production of creatinine raises serum creatinine concentrations, resulting in a measurable but small elevation.
Glomerular filtration rate remains unchanged, indicating that the elevated serum creatinine is due to increased production rather than reduced kidney filtration.
Evidence from Studies
Supporting (1)
Community contributions welcome
Effect of creatine supplementation on kidney function: a systematic review and meta-analysis
The study looked at 12 experiments with creatine and found that people taking it had a tiny bit more creatinine in their blood, but their kidneys were still working fine, just like the claim says.
Contradicting (0)
Community contributions welcome
Score Breakdown
No multi-axis breakdown available yet. The overall Pro / Against score above is the best signal.
- No clinical evidence is available; the score reflects mechanistic plausibility only.
What Would Prove This
Per GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this claim, ordered from strongest to weakest.
Meta-Analysis of Randomized Controlled Trials Assessing the Effect of Creatine Supplementation on Serum Creatinine Levels in Healthy Adults
A comprehensive search of databases for RCTs comparing creatine supplementation (3-5 g/day) to placebo in healthy adults, with serum creatinine measured at baseline and post-intervention, followed by meta-analysis using random or fixed effects models.
Double-Blind, Placebo-Controlled RCT of Creatine Supplementation (5 g/day for 8 weeks) on Serum Creatinine in Healthy Adults
Healthy adults (ages 18-50) randomized to receive either creatine monohydrate 5 g/day or an identical placebo for 8 weeks, with serum creatinine measured at baseline and end of study, and possibly a follow-up after washout.
Prospective Cohort Study of Creatine Supplement Users vs Non-Users and Changes in Serum Creatinine Over 1 Year
Follow a group of healthy adults who self-select to use creatine (at standard doses) and a matched non-user group, with serum creatinine measured at baseline, 6 months, and 12 months, adjusting for confounders like age, sex, exercise, and diet.
Case-Control Study of Creatine Users with Elevated Serum Creatinine vs Normal Levels
Identify cases with elevated serum creatinine (above normal range) and controls with normal levels, then retrospectively compare their past use of creatine supplements, controlling for other factors.
Cross-Sectional Study of Serum Creatinine Levels Across Creatine Supplementation Doses
Survey a sample of healthy adults, record current creatine use (dose and frequency), and measure serum creatinine once, comparing levels across users and non-users while controlling for confounders.