What is the correct expression for creatinine clearance?

• A. Creatinine clearance = U/P X V X 1.73/A
• B. Creatinine clearance = P/V X U X A/1.73
• C. Creatinine clearance = P/V X U X 1.73/A
• D. Creatinine clearance = U/V X P X 1.73/A

Answer: (A)

Creatinine clearance mirrors glomerular filtration by relating how much creatinine is excreted in urine to how much is present in plasma, adjusted for the volume of urine produced. The basic formula is clearance ≈ (urine creatinine concentration × urine flow rate) / plasma creatinine concentration. If you want to compare clearance across people of different body sizes, you normalize to a standard body surface area (1.73 m²) by multiplying by 1.73 and dividing by the individual's actual body surface area. Using U for urine creatinine, P for plasma creatinine, V for urine flow rate, and A for body surface area, the expression becomes (U × V) / P × (1.73 / A), which is written as U/P × V × 1.73/A. This matches the standard approach to report creatinine clearance normalized to 1.73 m².