Calc Function

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    • Subcategory of 'Diagnosis' designed to be very sensitiveRule Out
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    Chief Complaint


    Organ System


    Patent Pending

    Absolute Lymphocyte Count (ALC)

    Assesses number of lymphocytes and predicts CD4 count.


    Tips for COVID-19: Use after diagnosis to determine dispo. Lymphopenia appears to be a predictor of COVID infection.

    When to Use
    Why Use

    • Frequently used in the ED setting because CD4 tests take longer to come back and need patient consent.

    • Used in limited-resource settings where CD4 tests are costly or unavailable.

    • If the ALC is low, the CD4 will usually be low (Shapiro 1998).

    • Currently evidence is mostly around HIV-1 treatment-naive patients.

    • Other viral infections such as influenza or EBV can cause lymphopenia.

    • Does not aid in the diagnosis of HIV.

    Serves as a surrogate for CD4 count in HIV patients who are naive to antiretroviral therapy in resource-limited areas.

    × 10³ cells/µL
    Confirmed positive
    Confirmed negative


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    Next Steps
    Creator Insights
    Dr. Nathan Shapiro

    About the Creator

    Nathan Shapiro, MD, is an attending physician in the Department of Emergency Medicine at Beth Israel Deaconess Medical Center. He is also a director at the Center for Vascular Biology Research and an assistant professor at Harvard Medical School. Dr. Shapiro conducts translational and clinical research with a particular focus on endothelial cell dysfunction in sepsis.

    To view Dr. Nathan Shapiro's publications, visit PubMed

    Are you Dr. Nathan Shapiro? Send us a message to review your photo and bio, and find out how to submit Creator Insights!
    MDCalc loves calculator creators – researchers who, through intelligent and often complex methods, discover tools that describe scientific facts that can then be applied in practice. These are real scientific discoveries about the nature of the human body, which can be invaluable to physicians taking care of patients.
    Content Contributors
    • Alex Lazo, MD
    About the Creator
    Dr. Nathan Shapiro
    Are you Dr. Nathan Shapiro?
    Content Contributors
    • Alex Lazo, MD