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How to Calculate FEUrea

The Fractional Excretion of Urea (FEUrea) shows the ratio of urea in blood to urea in urine. An imbalance indicates two forms of Acute Renal Failure. A low ratio (less than 35 percent) indicates prerenal azotemia, while a high ratio (greater than 50 percent) indicates acute tubular necrosis (ATN).

Things You'll Need

  • Blood work analysis
  • Urinalysis
  • A calculator or a FEUrea app for smart phone
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Instructions

  1. Calculating FEUrea

    • 1

      Get a lab to do blood analysis and urinalysis on blood and urine samples.

    • 2

      Get the following data from the blood work and urinalysis: blood urea, urine urea, blood creatinine and urine creatinine.

    • 3

      Enter the data into the following formula (or enter into an online calculator or smart phone app): (urine urea / blood urea) / (urine creatinine/blood creatinine) * 100

    • 4

      If the resulting percentage is less than 35 percent, this indicates prerenal azotemia. If it is greater than 50 percent, this indicates acute tubular necrosis (ATN).

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