Calc Function

    • Calcs that help predict probability of a diseaseDiagnosis
    • Subcategory of 'Diagnosis' designed to be very sensitiveRule Out
    • Disease is diagnosed: prognosticate to guide treatmentPrognosis
    • Numerical inputs and outputsFormula
    • Med treatment and moreTreatment
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    Chief Complaint


    Organ System


    Patent Pending

    Fractional Excretion of Urea (FEUrea)

    Determines the cause of renal failure. Similar to the FENa, but can be used on patients on diuretics.

    While lesser known than FENa, the FEUrea can be used in patients on diuretics, since urea excretion is not significantly affected by diuretics.



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    Creator Insights


    In patients with acute kidney and suspected obstructive uropathy, consider bedside ultrasound to evaluate for hydronephrosis, bladder distention, etc. Empiric Foley catheter placement may also be valid in some settings, though it may also be associated with complications, and does not rule out ureteral obstructions above the bladder.


    Fractional Excretion of Urea (FEUrea) = (SerumCr * UUrea) / (SerumUrea x UCr) %

    Facts & Figures

    This test can provide similar information to the FENa equation, but can still be used in patients on diuretic therapy (diuretics alter the sodium concentration, making the FENa equation unusable).

    Prerenal Intrinsic Renal Postrenal
    FENa <1% >1% >4%
    FEUrea ≤ 35% >50% N/A
    Dr. Andre A. Kaplan

    About the Creator

    Andre A. Kaplan, MD, FACP, FASN, is a nephrologist at UConn Health. He is also a professor of medicine at University of Connecticut School of Medicine. Dr. Kaplan’s primary research is focused on kidney disease and dialysis.

    To view Dr. Andre A. Kaplan's publications, visit PubMed

    Dr. Orly F. Kohn

    About the Creator

    Orly F. Kohn, MD, is an associate professor of medicine at the University of Chicago Medicine. She is also the medical director of the Home Dialysis Unit at the University of Chicago. Dr. Kohn’s primary research is focused on diabetic nephropathy, home dialysis, and electrolyte disorders.

    To view Dr. Orly F. Kohn's publications, visit PubMed

    About the Creator
    Dr. Andre A. Kaplan
    Dr. Orly F. Kohn