Given the following information, calculate the creatinine clearance using the Cockcroft-Gault formula: Age = 85; weight = 70 kg; sex = male Serum creatinine = 1.0 mg/dL

Given the following information, calculate the creatinine clearance using the Cockcroft-Gault formula: Age = 85; weight = 70 kg; sex = male Serum creatinine = 1.0 mg/dL

• A. 53
• B. 72
• C. 47
• D. 35

Answer: (A)

The concept being tested is using the Cockcroft-Gault formula to estimate creatinine clearance from age, weight, sex, and serum creatinine. For a male, CrCl = [(140 − age) × weight] / (72 × Scr). Plugging in the values: (140 − 85) = 55; 55 × 70 = 3850. Denominator: 72 × 1.0 = 72. So CrCl = 3850 / 72 ≈ 53.5 mL/min, which rounds to about 53 mL/min. This matches the given option. The result makes sense here: advanced age lowers clearance, and the serum creatinine of 1.0 mg/dL with that age and weight yields a CrCl around the mid-50s. The other numbers are not consistent with this calculation.

The concept being tested is using the Cockcroft-Gault formula to estimate creatinine clearance from age, weight, sex, and serum creatinine. For a male, CrCl = [(140 − age) × weight] / (72 × Scr). Plugging in the values: (140 − 85) = 55; 55 × 70 = 3850. Denominator: 72 × 1.0 = 72. So CrCl = 3850 / 72 ≈ 53.5 mL/min, which rounds to about 53 mL/min. This matches the given option. The result makes sense here: advanced age lowers clearance, and the serum creatinine of 1.0 mg/dL with that age and weight yields a CrCl around the mid-50s. The other numbers are not consistent with this calculation.