From the Guidelines
Creatine supplements can increase creatinine levels in blood tests, but they do not affect blood urea nitrogen (BUN) levels, and this elevation does not indicate actual kidney damage or impaired renal function. According to a study published in the American Journal of Kidney Diseases 1, creatine supplementation can raise serum creatinine levels due to its metabolism to creatinine in the body. This is a crucial consideration for individuals, especially athletes and fitness enthusiasts, who take creatine supplements to enhance exercise performance and muscle development.
The study highlights that in a unique situation of using creatine supplementation in a patient with a solitary kidney, the use of creatinine did not alter kidney function; however, creatinine clearance measurements were incorrect, leading to a misclassification of acute kidney injury due to influences of creatine supplementation on creatinine clearance measurements 1. It is essential for individuals taking creatine supplements to inform their healthcare provider before blood tests to avoid misinterpretation of elevated creatinine levels as indicating kidney problems.
Key points to consider:
- Creatine supplements can increase creatinine levels in blood tests by approximately 0.3-0.4 mg/dL.
- This elevation is temporary and reversible, with creatinine levels typically returning to baseline after discontinuing creatine supplementation for 2-4 weeks.
- The increased creatinine is not due to kidney dysfunction but simply reflects higher creatine turnover.
- It is crucial to inform healthcare providers about creatine supplementation before blood tests to avoid misinterpretation of results.
From the Research
Creatine Supplements and Creatinine Levels
- Creatine supplements may increase serum creatinine levels, but this does not necessarily indicate kidney dysfunction, as creatine is spontaneously converted into creatinine 2, 3.
- The increase in serum creatinine levels may lead to an overdiagnosis of chronic renal failure, especially if the individual is also consuming a high-protein diet 3.
- Studies have shown that creatine supplementation does not significantly alter serum creatinine levels or plasma urea values in healthy individuals 4.
- However, it is recommended that creatine supplements not be used by individuals with pre-existing kidney disease or those at risk of kidney dysfunction 3, 5, 6.
Effects on Kidney Function
- Clinical trials with controlled designs have not supported the claim that creatine supplementation impairs kidney function 2.
- A prospective report found that short-term creatine supplementation did not affect kidney function in an individual with a single kidney and mildly decreased glomerular filtration rate (GFR) 5.
- A systematic review and meta-analysis found that creatine supplementation did not induce renal damage in the studied amounts and durations 4.
- However, further studies are needed to assess the safety of creatine supplements in individuals with pre-existing kidney disease 2, 6.
Safety and Recommendations
- Creatine supplements are generally considered safe for human consumption, but individuals with pre-existing kidney disease or those at risk of kidney dysfunction shouldn't use them 2, 3, 6.
- It is essential to monitor kidney function and serum creatinine levels in individuals taking creatine supplements, especially if they have any underlying kidney issues 5.
- More research is needed to fully understand the effects of creatine supplementation on kidney function and to provide clear recommendations for its use 2, 6.