Absolute Lymphocyte Count (ALC)
- Typically this is used in third world countries where CD4 tests are expensive or not available.
- Frequently used in the ED setting because CD4 tests take longer to come back and need patient consent.
- Lymphocytes include CD4, CD8, Natural Killer Cells, and a few others. CD4 is what gets attacked by HIV, and if it gets low enough, causes AIDS.
- Sometimes the ALC is called the “Poor Man's CD4” or the “Poor Doc's CD4.”
- If the ALC is low, the CD4 will usually be low (Shapiro NI 1998).
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- In the right clinical context, consider undiagnosed HIV as a cause of low lymphocyte count.
- Recall that many viral infections can cause leukopenia and lymphocytopenia, including but not limited to influenza, EBV, or even the common cold.
ALC = WBC count x 1000 x %lymphs
Facts & Figures
Predicted CD4 from ALC (van der Ryst E 1998)
|ALC||Predicted CD4 Count|
|< 1000 cells/mm3||< 200 cells/mm3|
|1000 - 2000 cells/mm3||Unable to predict|
|> 2000 cells/mm3||> 200 cells/mm3|
Original/Primary ReferenceShapiro NI, Karras DJ, Leech SH, Heilpern KL. Absolute lymphocyte count as a predictor of CD4 count. Ann Emerg Med. 1998 Sep;32(3 Pt 1):323-8.
Other Referencesvan der Ryst E, Kotze M, Joubert G, Steyn M, Pieters H, van der Westhuizen M, van Staden M, Venter C. Correlation among total lymphocyte count, absolute CD4+ count, and CD4+ percentage in a group of HIV-1-infected South African patients. J Acquir Immune Defic Syndr Hum Retrovirol. 1998 Nov 1;19(3):238-44.
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