eGFR Calculation for 41-Year-Old Patient
Calculated Result
Using the Cockcroft-Gault equation, the estimated creatinine clearance is approximately 88 mL/min, indicating normal kidney function for this patient. 1, 2
Calculation Method and Formula Selection
Cockcroft-Gault Equation (Recommended for Medication Dosing)
The Cockcroft-Gault formula is the most appropriate for this clinical scenario: 1, 2
CrCl (mL/min) = [(140 - age) × weight (kg)] / [72 × serum creatinine (mg/dL)] × (0.85 if female)
Converting Creatinine Units
- Your creatinine value of 96 appears to be in μmol/L (standard international units)
- To convert to mg/dL: 96 ÷ 88.4 = 1.09 mg/dL 2
Applying the Formula
For this patient:
- Age: 41 years
- Weight: 72.5 kg
- Creatinine: 1.09 mg/dL
- Gender: Not specified (assuming male for this calculation)
CrCl = [(140 - 41) × 72.5] / [72 × 1.09] = 7,177.5 / 78.48 ≈ 91 mL/min 1
If female: 91 × 0.85 ≈ 77 mL/min 1, 2
Alternative Calculation: MDRD Equation
The MDRD equation provides eGFR indexed to body surface area: 1
eGFR (mL/min/1.73 m²) = 175 × (serum creatinine)-1.154 × (age)-0.203 × (0.742 if female) × (1.212 if Black)
For this patient (assuming male, non-Black): eGFR = 175 × (1.09)-1.154 × (41)-0.203 = 175 × 0.906 × 0.738 ≈ 117 mL/min/1.73 m² 1
Clinical Interpretation
Normal Kidney Function Range
- Both calculations indicate normal kidney function 1, 3
- Normal GFR is approximately 130 mL/min/1.73 m² for men, with physiological decline of 0.75-1% per year starting after age 40 3, 4
- GFR ≥60 mL/min/1.73 m² does not meet criteria for chronic kidney disease 3
- This patient's values (88-117 mL/min depending on method) are well within normal range 1, 3
Key Clinical Caveats
Never use serum creatinine alone to assess kidney function - it is affected by muscle mass, age, sex, and race independent of actual GFR 1, 2, 3
- The Cockcroft-Gault equation is specifically recommended for medication dosing decisions because most drug dosing studies have historically used this formula 2
- The MDRD or CKD-EPI equations are preferred for diagnosing and staging chronic kidney disease as they provide GFR indexed to body surface area 1, 2, 3
- At this level of kidney function (>60 mL/min), both methods are clinically acceptable and indicate no renal impairment requiring medication dose adjustments 1, 3
Gender Consideration
If this patient is female, apply the 0.85 correction factor to Cockcroft-Gault (yielding ~77 mL/min) or the 0.742 factor to MDRD (yielding ~87 mL/min/1.73 m²) - both still indicating normal kidney function 1