Can taking creatine (creatine monohydrate) supplements cause elevated creatinine levels and impair renal (kidney) function?

Creatine Supplementation and Serum Creatinine Elevation

Creatine monohydrate supplementation causes elevated serum creatinine levels without impairing actual kidney function—the elevation is a laboratory artifact from creatine metabolism, not true kidney damage. 1, 2

Mechanism of Creatinine Elevation

• Creatine supplements spontaneously convert to creatinine through non-enzymatic degradation, increasing serum creatinine by approximately 0.2-0.3 mg/dL without affecting actual glomerular filtration rate (GFR). 2, 3
• In a prospective case study, creatine supplementation (20g/day for 5 days, then 5g/day for 30 days) increased serum creatinine from 1.03 to 1.27 mg/dL while measured GFR by 51Cr-EDTA clearance remained completely unchanged (81.6 vs 82.0 mL/min/1.73m²). 2
• This creates a false appearance of acute kidney injury that can lead to misdiagnosis of chronic kidney disease when none exists. 1

Why eGFR Calculations Are Unreliable with Creatine Use

• eGFR formulas incorporating serum creatinine are unreliable in patients with high muscle mass or creatine supplementation. 1
• eGFR calculations assume steady-state conditions and are invalid when creatinine is acutely elevated from non-renal causes such as creatine supplementation and intense exercise. 1
• Estimated creatinine clearance can falsely decrease by 15-20%, demonstrating how creatine supplementation leads to misclassification of kidney injury. 1
• Serum creatinine alone should never be used to assess kidney function due to confounding factors like muscle mass and creatine metabolism. 1

Evidence of Safety in Healthy Individuals

• Meta-analysis of 15 studies found that creatine supplementation (5-30 g/day for 5 days to 5 years) did not significantly alter true kidney function markers in healthy athletes. 4
• Short-term and long-term creatine supplementation had no significant effects on glomerular filtration rate in healthy athletes and bodybuilders without underlying kidney disease. 5
• Clinical trials with controlled designs do not support claims that creatine impairs kidney function, despite a few isolated case reports. 6

Diagnostic Approach When Creatinine Is Elevated

Do not diagnose kidney disease based on elevated serum creatinine alone in patients taking creatine supplements. 1

Essential Additional Testing:

• Obtain urinalysis with microscopy to look for proteinuria, hematuria, cellular casts, or acanthocytes that would indicate true intrinsic kidney disease. 1
• Check spot urine albumin-to-creatinine ratio as albuminuria indicates glomerular damage and true kidney disease—this should be normal with creatine supplementation. 1
• Consider cystatin C measurement as an alternative marker of kidney function that is not affected by muscle mass or creatine supplementation. 1
• Measure actual GFR using 51Cr-EDTA clearance or iothalamate clearance if diagnostic uncertainty persists, as these are unaffected by creatine metabolism. 2

Diagnostic Criteria for True CKD:

• CKD requires evidence of kidney damage or reduced GFR persisting for at least 3 months. 1
• A single elevated creatinine in the context of creatine supplementation and recent exercise does not establish CKD diagnosis. 1
• If urinalysis, albumin-to-creatinine ratio, and cystatin C are all normal, the elevated creatinine is artifactual. 1

Populations Who Should Avoid Creatine

Patients with pre-existing chronic kidney disease (GFR <45 mL/min/1.73m²) should avoid creatine supplementation entirely. 1

• The American Journal of Kidney Diseases explicitly discourages creatine supplementation in kidney donors due to their solitary kidney status and need to preserve remaining renal function. 1
• Individuals with diabetes or hypertension (risk factors for kidney dysfunction) should use creatine with caution and close monitoring. 5
• Patients using potentially nephrotoxic medications (NSAIDs, certain antibiotics) should avoid creatine. 3

Management When Creatinine Elevation Is Discovered

• Discontinue creatine supplementation immediately if there is diagnostic uncertainty about kidney function. 1
• Repeat serum creatinine and GFR measurements within 1-2 weeks after cessation to assess true baseline kidney function. 1
• After discontinuation, it takes approximately 4-6 weeks for creatinine levels to return to baseline. 7
• If renal function continues to decline despite discontinuation of creatine, nephrology referral is warranted as this suggests true kidney disease. 1

Common Pitfall to Avoid

The most critical error is discontinuing ACE inhibitors or ARBs based on creatinine elevation from creatine supplementation. Small elevations in serum creatinine (up to 30% from baseline) with RAS blockers must not be confused with acute kidney injury and should not prompt medication discontinuation in the absence of volume depletion. 8