Which expression represents the Cockcroft-Gault equation for creatinine clearance?

• A. ([140 - age] / serum creatinine) × (weight/72)
• B. ([140 - age] × weight) / (serum creatinine × 72)
• C. ([140 - age] / serum creatinine) × (72/weight)
• D. ([140 - age] × weight) / (serum creatinine + 72)

Answer: (A)

Estimating creatinine clearance with the Cockcroft-Gault equation uses age, weight, and serum creatinine to approximate kidney function for dosing. The standard form is CrCl ≈ [(140 − age) × weight (kg)] / [72 × serum creatinine (mg/dL)], with an adjustment of ×0.85 for females. The expression shown matches this because dividing by serum creatinine and multiplying by weight, then dividing by 72, is algebraically the same as multiplying (140 − age) by weight and dividing by (72 × serum creatinine). This yields CrCl in mL/min. Remember to use proper units (weight in kg, serum creatinine in mg/dL) and apply the female adjustment when appropriate.