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    Patent Pending

    Free Water Deficit in Hypernatremia

    Calculates free water deficit by estimated total body water.
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    Pearls/Pitfalls
    This tool provides an estimate of free water deficit based on a patient's body weight; this can be incorrect in patients with signfiicant weight gain or loss (especially from fluid sources).
    Female
    Male
    Child
    Adult
    Elderly
    lbs
    mEq/L
    mEq/L

    Result:

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    Evidence
    Creator Insights

    Advice

    After determining volume status, some patients with hypernatremia may improve with simple oral intake, while others may require further fluid management (and treatment of the underlying cause of the hypernatremia).

    Formula

    Free water deficit = % total body water, fraction × weight, kg × (current Na / ideal Na – 1)

    where % total body water (TBW) is:

    • Adult male: 60% (i.e., use 0.6 in the equation)
    • Adult female: 50% (0.5)
    • Elderly male: 50% (0.5)
    • Elderly female: 45% (0.45)
    • Child: 60% (0.6)
    Dr. Nicolaos E. Madias

    About the Creator

    Nicolaos E. Madias, MD is the chair of the department of medicine at the St. Elizabeth's Medical Center and a professor of medicine, specializing in Nephrology, at Tufts University School of Medicine. He has co-authored over 100 articles published in peer reviewed journals.

    To view Dr. Nicolaos E. Madias's publications, visit PubMed