Does creatine supplementation cause kidney damage in a healthy individual without pre-existing kidney disease?

Is Creatine Damaging to Your Kidneys?

Creatine supplementation does not cause kidney damage in healthy individuals without pre-existing kidney disease, but it does elevate serum creatinine levels through non-pathologic conversion, which can falsely suggest kidney dysfunction when using standard eGFR calculations. 1, 2, 3

The Core Issue: Diagnostic Confusion, Not Actual Kidney Damage

The primary concern with creatine is not nephrotoxicity but rather diagnostic misinterpretation:

• Creatine supplementation increases serum creatinine by 0.2-0.3 mg/dL through spontaneous conversion to creatinine, not through kidney damage 1, 3
• This elevation creates a false appearance of acute kidney injury that can lead to misdiagnosis of chronic kidney disease when none exists 1
• eGFR formulas incorporating serum creatinine are unreliable in patients with high muscle mass or creatine supplementation, with moderate strength of evidence 1
• In one prospective case study, creatine supplementation increased serum creatinine from 1.03 to 1.27 mg/dL while measured GFR by 51Cr-EDTA clearance remained completely unchanged 1

Evidence of Safety in Healthy Populations

Multiple systematic reviews and meta-analyses demonstrate renal safety:

• A 2019 meta-analysis of 15 studies found that creatine supplementation did not significantly alter serum creatinine levels (when accounting for the non-pathologic conversion) and did not alter plasma urea values 2
• Short- and long-term supplementation (5 days to 5 years) with doses ranging from 5-30 g/day showed no significant effects on glomerular filtration rate in healthy athletes without underlying kidney disease 4
• Clinical trials with controlled designs consistently fail to support claims of kidney dysfunction, despite a few isolated case reports 3

Who Should Avoid Creatine

Absolute contraindications based on nephrology consensus:

• Patients with pre-existing chronic kidney disease (GFR <45 mL/min/1.73m²) should avoid creatine entirely 1
• Individuals with a solitary kidney should not use creatine due to critical need to preserve remaining renal function 1
• Kidney donors are explicitly discouraged from creatine supplementation by nephrology expert consensus 1

Relative contraindications requiring caution:

• Patients with diabetes, hypertension, or reduced glomerular filtration rate should avoid high-dose (>3-5 g/day) supplementation 5
• Those using potentially nephrotoxic medications (NSAIDs, certain antibiotics) should avoid combining these with creatine 1

Proper Kidney Function Assessment During Creatine Use

If kidney function assessment is needed in someone taking creatine:

• Use cystatin C-based GFR or measured GFR rather than serum creatinine or creatinine-based eGFR, as cystatin C is unaffected by muscle mass or creatine supplementation 1
• 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 1
• A single elevated creatinine in the context of creatine supplementation and recent exercise does not establish CKD diagnosis 1

Clinical Pitfalls to Avoid

• Never use serum creatinine alone to assess kidney function in creatine users due to confounding factors 1
• eGFR calculations assume steady-state conditions and are invalid when creatinine is acutely elevated from non-renal causes like creatine supplementation 1
• CKD requires evidence of kidney damage or reduced GFR persisting for at least 3 months, not a single elevated creatinine 1
• If diagnostic uncertainty exists, discontinue creatine and repeat measurements within 1-2 weeks to assess true baseline kidney function 1

Additional Metabolic Considerations

• Short-term high-dose creatine (20 g/day for 5-14 days) stimulates production of methylamine and formaldehyde in urine, but there is no definite clinical evidence of adverse effects on kidney function from these metabolites 4, 5
• The main side effect is a potential 1-2 kg increase in body mass, typically from water retention or increased protein synthesis, not kidney dysfunction 6