How much can Premier Protein shakes increase serum creatinine levels in a healthy adult?

Creatine Supplementation and Serum Creatinine Elevation

Direct Answer to Magnitude of Increase

Premier Protein shakes containing creatine can increase serum creatinine by approximately 0.2-0.3 mg/dL in healthy adults, which represents a false elevation that does not indicate kidney damage. 1, 2

Mechanism and Clinical Context

The elevation occurs through non-pathologic conversion of supplemental creatine to creatinine, not through kidney injury. 1 This creates a diagnostic challenge because:

• eGFR calculations will falsely decrease despite unchanged actual kidney function, potentially leading to misclassification of acute kidney injury when none exists. 1, 2
• In the prospective case study of a young man with a single kidney, creatine supplementation (20g/day for 5 days, then 5g/day for 30 days) increased serum creatinine from 1.03 to 1.27 mg/dL (a 0.24 mg/dL increase), while measured GFR by 51Cr-EDTA clearance remained completely unchanged (81.6 vs 82.0 mL/min/1.73m²). 2
• Estimated creatinine clearance falsely decreased from 88 to 71 mL/min/1.73m² in this same individual, demonstrating the magnitude of misclassification. 2

Dose-Response Relationship

The magnitude of creatinine elevation depends on the creatine dose in the protein shake:

• Loading doses (20g/day) produce the 0.2-0.3 mg/dL elevation described above. 2
• Maintenance doses (3-5g/day) produce proportionally smaller but still measurable elevations. 2, 3
• The effect is consistent across healthy individuals when using recommended doses. 3, 4

Critical Diagnostic Pitfall

Serum creatinine-based eGFR formulas are completely unreliable during creatine supplementation and should never be used alone to assess kidney function in this context. 1 The American Heart Association explicitly warns that eGFR calculations assume steady-state conditions and are invalid when creatinine is acutely elevated from non-renal causes like creatine supplementation. 1

Distinguishing False from True Elevation

To determine if the elevation represents false increase versus actual kidney damage:

• Obtain urinalysis with microscopy looking 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
• Consider cystatin C measurement as an alternative marker unaffected by muscle mass or creatine supplementation. 1
• In the case study, proteinuria remained unchanged (130 vs 120 mg/day) and albuminuria actually decreased (4.6 vs 2.9 mg/day), confirming no kidney damage occurred despite the creatinine rise. 2

Time Course and Reversibility

The creatinine elevation:

• Occurs within days of starting supplementation 2
• Persists throughout the supplementation period 2, 3
• Reverses within 1-2 weeks after discontinuation 1
• Does not indicate progressive kidney damage even with continued use at recommended doses 4

Safety Evidence

A systematic review and meta-analysis found that creatine supplementation did not significantly alter serum creatinine levels in a clinically meaningful way (standardized mean difference = 0.48) and did not induce renal damage at studied amounts and durations. 4 However, this statistical finding reflects the heterogeneity of studies; individual increases of 0.2-0.3 mg/dL are well-documented but may not reach statistical significance across pooled populations. 2

Special Populations Requiring Caution

The American Journal of Kidney Diseases explicitly discourages creatine supplementation in kidney donors and individuals with solitary kidneys due to their critical need to preserve remaining renal function, despite direct evidence suggesting short-term safety. 1, 2 This reflects the evidence gap on long-term safety (>1 year) in vulnerable populations. 1

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