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24-Hour Creatinine Clearance Calculator

Enter urine and plasma creatinine (in the same unit), the urine volume and the collection time. Add height and weight to normalise the result to 1.73 m² body surface area.

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For learning and checking your own calculations. Always follow your laboratory's SOPs and verified procedures.

Good to know

CrCl (mL/min) = (urine creatinine × urine volume) ÷ (plasma creatinine × time in minutes). BSA (Mosteller) = √(height × weight ÷ 3600); normalised CrCl = CrCl × 1.73 ÷ BSA. Incomplete collections are the most common error: check total urine creatinine excretion against what is expected for the patient's size. Creatinine clearance slightly overestimates true GFR because some creatinine is secreted by the kidney tubules.

Formula

CrCl (mL/min) = (urine creatinine × urine volume mL) ÷ (plasma creatinine × minutes)

BSA (Mosteller) = √(height cm × weight kg ÷ 3600)

Normalised CrCl = CrCl × 1.73 ÷ BSA

Common questions

How is creatinine clearance calculated?

(Urine creatinine × urine volume) ÷ (plasma creatinine × time in minutes), with both creatinine values in the same unit.

Why normalise to 1.73 m²?

It allows comparison between people of different body sizes. Normalised CrCl = CrCl × 1.73 ÷ BSA.

What is the most common error in 24-hour urine collection?

An incomplete collection, which gives a falsely low clearance.

Sources