Can creatinine monohydrate cause a false rise in creatinine levels in blood tests?

From the Guidelines

No, creatine monohydrate supplements do not cause false rises in creatinine levels in blood tests, but rather actual, temporary elevations in serum creatinine. When you take creatine monohydrate supplements, some of it is metabolized to creatinine, which is then filtered by the kidneys and measured in blood tests. This elevation represents a true increase in creatinine production rather than a laboratory error or false positive, as supported by the understanding that serum creatinine concentration is affected by factors other than GFR, such as creatinine secretion and generation and extrarenal excretion 1. The effect is typically modest, with increases of about 0.1-0.2 mg/dL in serum creatinine levels, though it can be higher with larger supplementation doses.

Key Considerations

• The serum creatinine concentration has a relatively wide range in normal persons, meaning GFR must decline significantly before serum creatinine rises above normal limits 1.
• Clinical laboratories should report an estimate of GFR using a prediction equation in addition to serum creatinine measurement to accurately assess kidney function 1.
• If you're taking creatine supplements and need accurate kidney function assessment, it's advisable to temporarily discontinue the supplement 24-48 hours before blood testing to allow creatinine levels to return to baseline.

Recommendations for Clinical Practice

• Always inform your healthcare provider about any supplements you're taking, as this information helps them interpret your laboratory results correctly.
• Be aware that differences in calibration of serum creatinine assays among clinical laboratories can lead to errors in GFR estimates, emphasizing the need for standardized calibration 1.

From the Research

Creatinine Monohydrate and Blood Test Results

• Creatinine monohydrate supplementation may cause a false rise in creatinine levels in blood tests, as reported in several studies 2, 3.
• This increase in creatinine levels can lead to an overdiagnosis of chronic renal failure, especially if the individual is also consuming a high protein diet 2.
• However, it is essential to note that creatine supplementation is generally considered safe and does not cause renal disease in healthy individuals 4, 5.

Effects on Renal Function

• Some studies suggest that creatine supplementation may not significantly alter serum creatinine levels or plasma urea values 5.
• However, individuals with pre-existing kidney disease or those taking potentially nephrotoxic medications shouldn't use creatine supplements, as they may be associated with an increased risk of renal dysfunction 4, 3.
• The existing literature indicates that creatine supplementation appears safe when used by healthy adults at recommended doses, but more research is needed to fully understand its effects on renal function 4, 3.

Key Findings

• Creatine monohydrate supplementation can cause a temporary rise in serum creatinine levels, which may mimic kidney disease 2.
• Clinical laboratories should be aware of this potential effect when interpreting blood test results, especially in individuals who use creatine supplements 2, 3.
• Further studies are necessary to investigate the long-term effects of creatine supplementation on renal function and to establish its safety in children and adolescents 3, 5.