The fractional urea excretion represents the percent of filtered urea to reach the urine and is an index of the renal ability to excrete urea. This is the same as the ratio of urea clearance divided by creatinine clearance.


Testing can be performed on a spot urine specimen or a 24 hour urine.


fractional excretion of urea (FE-urea) =

= (100% * (((urine urea in mmol/L) / (plasma urea in mmol/L)) / ((urine creatinine in µmol/L) / (plasma creatinine in µmol/L))))


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