Can a surgeon assume elevated creatinine (Creatinine) levels in a patient with impaired renal function, due to creatine supplementation, and proceed with a hysterectomy?

Preoperative Risk Assessment: Creatine Supplementation and Elevated Creatinine

The surgeon should NOT assume the elevated creatinine is solely from creatine supplementation and should NOT proceed with surgery without further evaluation, as this patient has Stage 3B chronic kidney disease (eGFR 37) that represents a significant independent risk factor for perioperative morbidity and mortality.

Critical Analysis of This Patient's Renal Function

This 61-year-old woman presents with concerning renal parameters that cannot be dismissed as supplementation artifact:

• The eGFR of 37 mL/min/1.73m² indicates Stage 3B chronic kidney disease, which falls well below the threshold for moderate renal impairment 1
• The BUN/Creatinine ratio of 8 is abnormally LOW (normal is 10-20), which actually suggests chronic intrinsic renal disease rather than prerenal azotemia or simple creatinine elevation from supplementation
• The creatinine of 1.57 mg/dL, while below the 2.0 mg/dL threshold cited in guidelines, still represents significant renal impairment when combined with the eGFR 2

Why Creatine Supplementation Cannot Explain These Findings

While creatine supplementation can transiently elevate serum creatinine, the evidence shows:

• Creatine supplementation causes a modest increase in serum creatinine (typically 0.2-0.3 mg/dL) without affecting actual glomerular filtration rate 3, 4
• In a controlled study, creatine supplementation increased serum creatinine from 1.03 to 1.27 mg/dL while measured GFR remained unchanged (81.6 to 82.0 mL/min/1.73m²) 3
• The LOW BUN/Creatinine ratio of 8 in this patient is inconsistent with isolated creatine supplementation, which would not suppress BUN disproportionately 5
• If this were purely supplementation-related, the eGFR would be falsely low but actual kidney function would be preserved—however, the clinical picture suggests true renal impairment

Perioperative Risk Based on ACC/AHA Guidelines

The ACC/AHA guidelines for perioperative cardiovascular evaluation establish clear risk thresholds:

• Preoperative creatinine ≥2.0 mg/dL is an independent risk factor for cardiac complications after major noncardiac surgery 2
• Reduced glomerular filtration rate (which this patient has at 37 mL/min/1.73m²) is identified as a risk factor for postoperative renal dysfunction and increased long-term morbidity and mortality 2
• The guidelines emphasize that eGFR calculated by the MDRD equation provides more accurate assessment than serum creatinine alone 2
• Relying solely on serum creatinine underestimates renal impairment, particularly in older patients and women 6

Mandatory Preoperative Actions

Before proceeding with hysterectomy, the following steps are essential:

1. Discontinue creatine supplementation for at least 2-4 weeks and repeat renal function testing to determine if creatinine normalizes while monitoring eGFR 7, 5

2. If eGFR remains <45 mL/min/1.73m² after creatine cessation, obtain nephrology consultation before proceeding with elective surgery 1

3. Investigate the cause of the low BUN/Creatinine ratio, as this suggests chronic kidney disease rather than supplementation artifact and may indicate underlying renal pathology requiring workup

4. Assess for additional risk factors including diabetes, hypertension, cardiovascular disease, and use of nephrotoxic medications that compound perioperative risk 2, 1

5. If surgery must proceed urgently, implement renal-protective measures including adequate hydration, avoidance of nephrotoxic agents, and close postoperative monitoring of renal function 1

Common Pitfalls to Avoid

• Do not assume elevated creatinine is benign without confirming actual GFR through cessation of supplementation and repeat testing 3, 5
• Do not rely on the creatinine value alone when eGFR indicates Stage 3B kidney disease, as this represents true renal impairment regardless of supplementation 2, 6
• Do not ignore the abnormally low BUN/Creatinine ratio, which is a red flag for intrinsic renal disease rather than supplementation effect
• Do not proceed with elective surgery in a patient with eGFR <40 mL/min/1.73m² without nephrology input, as this significantly increases risk of postoperative complications including progression to dialysis 2

The evidence is clear that creatine supplementation is safe and does not cause true renal dysfunction 7, 4, but this patient's constellation of findings—particularly the eGFR of 37 and low BUN/Creatinine ratio—suggests underlying chronic kidney disease that requires evaluation before elective surgery.