Short answer: It can raise blood creatinine, the main kidney marker on routine labs. A 2026 meta-analysis of randomized trials found creatinine about 0.13 mg/dL higher with creatine, with no clear change in urea or estimated kidney function (eGFR). Because creatinine comes from muscle, MedlinePlus says a high result does not always mean a kidney problem, and asks you to tell your provider what supplements you take.
MedlinePlus describes creatinine as a normal waste product made when you use your muscles and some muscle tissue breaks down. Most routine kidney checks report blood creatinine and use it to calculate an eGFR, an estimate of how well the kidneys filter.
MedlinePlus also says people make different amounts of creatinine depending on how much muscle they have, what they eat, their age and how active they are. It lists dehydration, muscle injury, intense exercise and a diet high in meat as reasons creatinine can be high without kidney disease, says some people are told to skip meat for 24 hours before the test, and says certain medicines and supplements can affect results.
| Study | What it found |
|---|---|
| Tsiaras 2026, 19 randomized trials plus 1 crossover | Creatinine about 0.13 mg/dL higher; no difference in urea or eGFR |
| Naeini 2025, 21 studies | Small rise in creatinine, judged to reflect turnover rather than kidney harm; no significant change in GFR |
| Gualano 2008, 18 men, about 10 g a day for 3 months | No sign of kidney dysfunction; cystatin C fell in both groups with training |
Tsiaras and colleagues found no difference between trials shorter or longer than a month, and called for trials longer than a year. The abstracts do not report results for people with kidney disease, so these findings do not speak to them.
The NIDDK says eGFR is an estimate, not a precise measure, and that using both creatinine and cystatin C is preferred and more accurate than creatinine alone. Cystatin C is a second blood marker of kidney filtering, and the Gualano trial used it to check kidney function alongside creatinine.
The NIDDK also says kidney function is best read from trends over time using the same equation, rather than from one result. A single slightly high creatinine in someone taking creatine is a reason for context, not a diagnosis.
MedlinePlus asks you to tell your provider everything you take before the test, and not to stop any medicine unless told to. For creatine, useful details are how much you take, since when, and whether you started a new training block or diet. The same idea applies to biotin and blood tests.
Whether to pause creatine before a test, or to add cystatin C, is the provider's call. Dose Track can log supplements and lab results on one timeline, so the start date sits next to the creatinine trend.
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