The evidence-led answer
NST verdict
The cited short trials provide reassurance for the populations and protocols studied, not a guarantee for every reader. Creatine can influence creatinine-based kidney estimates, but that does not establish why an individual result is abnormal. Do not dismiss a raised creatinine or lower eGFR as a supplement effect without clinical assessment.
Does creatine damage healthy kidneys?
The cited trials are limited to specific populations and protocols. In a 12 week randomised, placebo controlled trial, resistance trained people already eating a high protein diet took creatine, a 5 day 20 g/day loading phase, then 5 g/day. Kidney filtration was measured with 51Cr EDTA clearance, a reference method, not an estimate, and showed no significant change; creatinine clearance, urea, electrolytes, protein in the urine and albumin in the urine all stayed put. A separate 12 week randomised trial in postmenopausal women used the same measured method and also found kidney filtration unchanged.
The 2023 narrative review discusses reassuring controlled evidence, but its conclusions must be read alongside study populations, duration and methods. It is not proof of universal safety.
Then why did my creatinine go up?
Creatine supplementation is one factor that can influence creatinine-based estimates of kidney function. An abnormal result can also reflect a kidney problem. Taking creatine does not, by itself, distinguish those possibilities.
Tell the clinician interpreting your results about all supplements you take. Follow their advice on further tests, timing and whether to change supplement use. This article cannot determine the cause or recommend a fixed stop-and-retest interval.
Who should be cautious?
If you have a kidney condition, reduced kidney function, are on dialysis or have a single kidney, seek individual medical advice before taking creatine. Evidence from other populations is not personal clearance. Trial duration, sample size and other differences also limit the evidence.
What this means in practice
Do not use this article to self-diagnose an abnormal kidney result or to choose a dose on the assumption that your kidneys are healthy. Tell your clinician about creatine and other supplements, and follow their investigation advice. Seek individual advice before starting if you have a kidney condition.
Practical meaning
Do not use this article to self-diagnose an abnormal kidney result or to choose a dose on the assumption that your kidneys are healthy. Tell your clinician about creatine and other supplements, and follow their investigation advice. Seek individual advice before starting if you have a kidney condition.
Limitations and uncertainty
The cited filtration trials are small and short. They do not establish safety for every population or explain an individual's abnormal result. Clinical interpretation and testing decisions belong with the treating clinician. Full-text and newer-evidence review remain outstanding.