Creatinine-corrected urine tests can still be performed in a person with elevated urine creatinine, but the results may be less accurate and should be interpreted with caution, as the correction method has inherent limitations that are amplified when creatinine excretion deviates significantly (multi-fold elevation) from average.
Concerns have been raised about the safety of creatine supplementation as it can increase serum creatinine, but a systematic review and meta-analysis found no effect on glomerular filtration rate (GFR), and concluded that creatine supplementation does not adversely affect kidney function.
For individuals supplementing with creatine who have elevated creatinine, a serum or plasma cystatin C-based eGFR* (estimated GFR) is recommended to assess kidney function. It is a highly accurate blood test used to measure how well the kidneys filter waste. Unlike traditional creatinine-based tests, cystatin C is not influenced by muscle mass, age, or diet, making it a superior marker for special populations, including those supplementing with creatine.
*Not available at Vibrant
References
- Naeini EK, Eskandari M, Mortazavi M, Gholaminejad A, Karevan N. Effect of creatine supplementation on kidney function: a systematic review and meta-analysis. BMC Nephrol. 2025;26(1):622. Published 2025 Nov 6. doi:10.1186/s12882-025-04558-6
- Spencer S, Desborough R, Bhandari S. Should Cystatin C eGFR Become Routine Clinical Practice? Biomolecules. 2023 Jul 5;13(7):1075. doi: 10.3390/biom13071075. PMID: 37509111; PMCID: PMC10377068.