Is it safe to take creatine (a dietary supplement) if I have concerns about my creatinine (waste product) levels and kidney function?

Creatine Supplementation and Kidney Function: Safety Assessment

Creatine supplementation is safe for individuals with normal kidney function, but it will artificially elevate serum creatinine levels without causing actual kidney damage—this creates a diagnostic challenge that requires alternative testing methods to accurately assess true kidney function. 1, 2

Understanding the Critical Distinction

Creatine (the supplement) and creatinine (the waste product) are biochemically related but clinically distinct:

• Creatine supplementation increases creatinine production because creatine is naturally converted to creatinine in muscle tissue 2
• This elevation in serum creatinine does NOT reflect kidney dysfunction—it reflects increased creatinine generation from higher muscle creatine stores 1, 2
• Serum creatinine alone should never be used to assess kidney function due to confounding factors like muscle mass and creatine metabolism 1

Safety Profile in Healthy Individuals

For people with normal baseline kidney function, creatine supplementation appears safe even with prolonged use:

• Studies up to 5 years show no adverse effects on actual kidney function when monitored by clearance methods and urine protein excretion 3
• Recommended dosing (loading: 20g/day for 5-7 days; maintenance: ≤3g/day) shows no change in true kidney functionality 4, 5
• The kidneys maintain normal function in healthy subjects supplementing with creatine over several months 4, 6

High-Risk Populations Who Should Avoid Creatine

The American Journal of Kidney Diseases explicitly recommends against creatine supplementation in specific populations:

• Individuals with pre-existing renal disease 7, 4
• Those with potential risk factors for renal dysfunction including diabetes, hypertension, or reduced glomerular filtration rate 4
• Patients taking nephrotoxic medications (NSAIDs, certain antibiotics) 7, 8
• Living kidney donors should discontinue all dietary supplements during evaluation and perioperative periods 7

Accurate Assessment of Kidney Function During Creatine Use

When creatine supplementation causes elevated creatinine, use these alternative methods to assess true kidney function:

Primary Diagnostic Approach

• Measure serum cystatin C and calculate eGFRcr-cys (combined creatinine-cystatin C equation) 2
• Cystatin C is unaffected by muscle mass or creatine supplementation, making it the ideal confirmatory test 2
• eGFR formulas incorporating only serum creatinine are unreliable in patients with high muscle mass or creatine supplementation 1

Additional Markers of True Kidney Disease

• Check spot urine albumin-to-creatinine ratio (UACR): normal is <30 mg/g creatinine 2
• Albuminuria indicates glomerular damage and true kidney disease 1
• Obtain urinalysis with microscopy to look for proteinuria, hematuria, cellular casts, or acanthocytes that would indicate intrinsic kidney disease 1

Diagnostic Pitfall to Avoid

• A case report documented creatine supplementation increasing serum creatinine from 1.03 to 1.27 mg/dL while measured GFR by 51Cr-EDTA clearance remained unchanged—demonstrating misclassification of acute kidney injury 7, 1
• CKD requires evidence of kidney damage or reduced GFR persisting for at least 3 months—a single elevated creatinine during creatine supplementation does not establish CKD diagnosis 1

Clinical Algorithm for Elevated Creatinine on Creatine

If serum creatinine is elevated in someone taking creatine supplements:

1. Do NOT diagnose kidney disease based on creatinine-based eGFR alone 1, 2
2. Order cystatin C-based eGFR as the definitive test 2
3. Check UACR and urinalysis to look for markers of true kidney disease 1, 2
4. Assess BUN/creatinine ratio: a ratio <10 argues strongly against true renal disease and suggests isolated creatinine elevation from increased generation 2
5. If cystatin C-based eGFR is normal and UACR is normal, nephrology referral is unnecessary 2

When to Discontinue Creatine and Reassess

If there is genuine concern about kidney function:

• Discontinue creatine supplementation immediately 1
• Repeat serum creatinine and GFR measurements within 1-2 weeks after cessation to assess true baseline kidney function 1
• Avoid other potentially nephrotoxic medications like NSAIDs during this assessment period 1

Monitoring Recommendations

For individuals who choose to use creatine despite concerns:

• Pre-supplementation investigation of kidney function should be considered for safety, though it appears unnecessary in normal healthy subjects 4
• Regular monitoring is compulsory to avoid any abnormal reactions during oral creatine supplementation 3
• If renal function continues to decline despite discontinuation of creatine, nephrology referral is indicated 1

Bottom Line

The elevation in creatinine from creatine supplementation is a measurement artifact, not kidney damage. The key is using cystatin C-based testing to distinguish between falsely elevated creatinine (harmless) and true kidney dysfunction (requires intervention). For healthy individuals without pre-existing kidney disease or risk factors, creatine supplementation does not cause kidney damage. 1, 2, 4, 3