Should patients take a creatinine supplement?

Should Patients Take Creatine Supplements?

For healthy individuals without kidney disease, creatine supplementation at 3-5 g/day is safe and does not cause kidney damage, but it should be avoided in patients with pre-existing chronic kidney disease (GFR <45 mL/min/1.73 m²), those with a solitary kidney, or individuals taking potentially nephrotoxic medications. 1, 2

Who Can Safely Take Creatine

Healthy individuals with normal kidney function can safely use creatine supplementation at maintenance doses of 3-5 g/day, with evidence supporting safety even with higher doses (up to 30 g/day) for periods up to 5 years. 2, 3, 4

• Athletes and active individuals benefit from creatine through improved high-intensity exercise performance, increased muscle strength and power, and enhanced training capacity by increasing phosphocreatine stores by approximately 20%. 2
• The primary side effect is a 1-2 kg body mass increase due to water retention or increased protein synthesis, not kidney damage. 2
• Short-term and long-term supplementation shows no detrimental effects on kidney function in healthy populations, including both young and older individuals. 4, 5

Critical Contraindications: Who Should NOT Take Creatine

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

• Living kidney donors with solitary kidneys should not use creatine due to the critical need to preserve remaining renal function. 1, 2
• Individuals with pre-existing renal disease or risk factors for kidney dysfunction (diabetes, hypertension, reduced GFR) should avoid creatine supplementation. 1, 4
• Patients taking potentially nephrotoxic medications (NSAIDs, certain antibiotics) should not combine these with creatine. 1, 6

The Creatinine Confusion: A Critical Diagnostic Pitfall

Creatine supplementation increases serum creatinine by 0.2-0.3 mg/dL through non-pathologic conversion to creatinine, which falsely suggests kidney injury without actual kidney damage. 1, 7

• eGFR formulas incorporating serum creatinine are unreliable in patients taking creatine supplements because they assume steady-state conditions and cannot distinguish between creatinine from kidney dysfunction versus creatinine from creatine metabolism. 1
• A prospective case study demonstrated that creatine supplementation increased serum creatinine from 1.03 to 1.27 mg/dL while measured GFR by ⁵¹Cr-EDTA clearance remained completely unchanged at 81.6-82.0 mL/min/1.73 m². 1, 7
• This creates a false appearance of acute kidney injury that can lead to misdiagnosis of chronic kidney disease when none exists. 1, 3

Proper Kidney Function Assessment in Creatine Users

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. 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
• Cystatin C measurement provides an alternative marker of kidney function that is not affected by muscle mass or creatine supplementation. 1
• If diagnostic uncertainty exists, discontinue creatine supplementation immediately and repeat serum creatinine and GFR measurements within 1-2 weeks to assess true baseline kidney function. 1

Recommended Supplementation Protocol (For Appropriate Candidates)

The maintenance dose is 3-5 g/day as a single dose for the duration of supplementation. 2

• Consuming creatine with approximately 50g each of protein and carbohydrate enhances muscle uptake via insulin stimulation. 2
• A loading phase (20 g/day for 5 days) is optional but not necessary for achieving benefits. 7
• Maintain consistent hydration and avoid intense exercise 24 hours prior to any kidney function testing to prevent confounding results. 1

Special Populations Requiring Extra Caution

Patients with diabetes and kidney disease should avoid creatine supplementation, especially when eGFR <45 mL/min/1.73 m². 1

• Small elevations in creatinine (up to 30% from baseline) may occur with ACE inhibitors or ARBs, which can be confused with creatine effects and should not automatically prompt medication discontinuation in the absence of volume depletion. 8, 1
• Referral to a nephrologist is recommended when eGFR <30 mL/min/1.73 m² or when there are persistently increasing levels of albumin in the urine. 1
• Blood pressure should be well-controlled (<130/80 mmHg) before considering creatine in any at-risk population. 1

Evidence Quality and Clinical Bottom Line

The evidence consistently demonstrates that creatine does not cause kidney disease in healthy individuals, despite numerous case reports and concerns. 6, 3, 4, 5

• Clinical trials with controlled designs do not support claims of kidney damage from creatine supplementation. 3
• The nephrology community's caution reflects the evidence gap on long-term safety (>1 year) in vulnerable populations rather than demonstrated harm in healthy individuals. 1
• The key is proper patient selection: healthy individuals can use creatine safely, while those with compromised kidney function or solitary kidneys should avoid it entirely. 1, 2, 4