The ability of the kidney to clear urea correlates with its level of function. Urea clearance has been largely supplanted by the creatinine clearance.


urea clearance in mL/min =

= ((urine urea output in mg/day) * 100) / ((blood urea in mg/dL) * 1440)


An alternative form is:


urea clearance in mL/min =

= ((urine urea output in mmol/day) * 1000) / ((blood urea in mmol/L) * 1440)


This can be "standardized" to a body surface area of 1.73 square meters in the same way as the creatinine clearance:


standardized urea clearance =

= calculated urea clearance * (1.73 / (BSA in square meters))



• 1.73 is the BSA of the "average-sized" person in square-meters.


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