What is the eGFR of a 53-year-old male with a serum creatinine level of 100.43 umol/L?

eGFR Calculation for 53-Year-Old Male with Creatinine 100.43 µmol/L

The estimated GFR (eGFR) for this patient is approximately 68-70 mL/min/1.73 m², indicating normal kidney function for his age. 1

Calculation Method

Use the CKD-EPI equation (refit without race variable) as the preferred method for GFR estimation, as it provides superior accuracy compared to older formulas, particularly at GFR values >60 mL/min/1.73 m². 1

Converting Units

• Serum creatinine: 100.43 µmol/L = 1.14 mg/dL (conversion factor: 1 mg/dL = 88.4 µmol/L) 2

Alternative Calculation Using MDRD

If using the MDRD equation (widely validated but less accurate at higher GFR values): 2, 1

• eGFR = 175 × (1.14)^-1.154 × (53)^-0.203 = approximately 68 mL/min/1.73 m² 1, 3

Cockcroft-Gault Formula

The older Cockcroft-Gault equation requires body weight and is less accurate than MDRD for CKD assessment: 2

• Formula: [(140 - age) × body weight (kg)] / [72 × serum creatinine (mg/dL)] 2
• This method is not recommended as it can overestimate creatinine clearance in CKD stages 3-5 1

Clinical Interpretation

This eGFR of 68-70 mL/min/1.73 m² represents normal kidney function for a 53-year-old male. 1

• Normal GFR is approximately 130 mL/min/1.73 m² for men, with a mean decline of 0.75 mL/min/year starting in the third or fourth decade 2, 1
• An eGFR ≥60 mL/min/1.73 m² does not meet criteria for chronic kidney disease (CKD) 2
• CKD is defined as eGFR <60 mL/min/1.73 m² or presence of albuminuria ≥30 mg/g creatinine 2

Important Clinical Caveats

Never rely on serum creatinine alone to assess kidney function, as it is affected by multiple non-GFR factors including muscle mass, creatinine generation, tubular secretion, and extrarenal excretion. 1

Factors That Can Falsely Elevate Creatinine

• Recent vigorous exercise within 24 hours 1, 3
• Creatine-containing dietary supplements (can significantly increase serum creatinine independent of kidney function) 4, 5
• High muscle mass 1, 4
• Acute infection, fever, marked hyperglycemia, or uncontrolled hypertension 1, 3

When eGFR May Be Inaccurate

• Extremes of muscle mass (very high or very low) 1
• Obesity or amputees 1
• Non-steady-state conditions 1
• Patients >70 years (consider BIS1 equation instead) 6

Laboratory Reporting Standards

Clinical laboratories should report eGFR rounded to the nearest whole number using units of mL/min/1.73 m². 2

• Creatinine should be measured using enzymatic methods where possible (more specific than Jaffe method) 2
• Coefficient of variation should be <2.3% for creatinine assays 2
• eGFR values <60 mL/min/1.73 m² should be flagged as low 2