During creatine supplementation, creatinine levels in the blood or urine may increase slightly because part of creatine is naturally converted into creatinine in the body. An increase in creatinine alone therefore does not automatically indicate kidney damage.
Meta-analyses show that, in healthy individuals taking standard doses of approximately 3–5 g per day, there is no significant deterioration in kidney function, such as a reduction in glomerular filtration rate (GFR). Creatine monohydrate is generally considered safe when the recommended dosage is followed. However, caution is appropriate in people with pre-existing kidney disease. [16]
