Use this tool to reproduce the documented calculation from laboratory values reported in the required units. It can support verification and education when the applicable patient population and convention are known.

Urine volume

Total urine volume collected; must be greater than zero.

Urine creatinine

Urine creatinine concentration; must be greater than zero.

Plasma creatinine

Plasma creatinine concentration; must be greater than zero.

Collection time

Collection period length; must be greater than zero.

The implementation follows this calculation rule: Compute renal creatinine clearance as urine volume times urine creatinine divided by plasma creatinine and the collection time in minutes.^[1]

Creatinine clearance

Creatinine clearance in millilitres per minute.

Calculated laboratory indices are not diagnoses and must not replace clinical interpretation. Assay method, reference interval, age, body size, medications, acute illness, unit conversion, and the population in which an equation was validated can change its meaning. Ratios and percentages become unstable when their denominator is small, uncertain, or defined differently between samples.

Review the original laboratory report, reference interval, trends, and relevant confirmatory tests. When an estimated physiologic quantity matters clinically, use the locally recommended equation or a measured method.

• Cockcroft-Gault CrCl

  Estimate creatinine clearance with the Cockcroft-Gault equation.

• MDRD eGFR

  Estimate glomerular filtration rate with the four variable MDRD equation.

• BUN Creatinine Ratio

  Compute the blood urea nitrogen to serum creatinine ratio.