Absolute Lymphocyte Count (ALC) Calculator

How does this absolute lymphocyte count (ALC) calculator work?

This ALC calculator is a health tool that is used to predict the CD4 count out of the number of lymphocytes where means to laboratory count them are not available.

White blood cell differential count is a laboratory blood testing method (usually part of the full blood count) put in place in order to diagnose conditions that affect the immune system:

■ Infections;

■ Inflammatory illnesses;

■ Immune deficiency;

■ Tumors (leukaemia, lymphoma).

There are five types of white blood cells, all produced in the lymphoid system in the bone marrow, each of them with a different immune function and all present in a relatively stable proportion:

■ Neutrophils – increased in bacterial infections, inflammatory disease and decreased in severe infections, liver or spleed diseases.

■ Lymphocytes (28 - 55%) – increased in bacterial, viral infections, leukaemia, spleen conditions, lupus or HIV infections.

■ Monocytes – increased in some leukaemias and decreased in bone marrow injury.

■ Eosinophils – increased as response to allergic reactions, skin inflammation or parasitic infections.

■ Basophils – increased in leukaemia, radiation therapy and long term inflammation.

Absolute lymphocytes normal range is between 1.3 and 3.5 x 10⁹/L and is calculated by the following formula:

ALC = WBC count x 1000 x % lymphocyte in WBC.

CD4 count

CD4 count testing is very elaborate and takes longer times, therefore often an estimation from the absolute lymphocyte count is used instead.

The following table presents the correlation between ALC levels and CD4 levels.

CD4 T lymphocytes are one of the immune indicators in blood in general and the most important laboratory immune indicator in patients with HIV and is often used as progression predictor and antiretroviral therapy monitor.

HIV attacks and destroys CD4 cells and uses them as a frame to further spread through the body.

Normal CD4 count ranges from 500 to 1,200 cells/mm³ and a count of less than 200 cells/mm³ is indicative of HIV progression to AIDS.

References

1) Shapiro NI, Karras DJ, Leech SH, Heilpern KL. (1998) Absolute lymphocyte count as a predictor of CD4 count. Ann Emerg Med; 32(3 Pt 1):323-8.

2) van der Ryst E, Kotze M, Joubert G, Steyn M, Pieters H, van der Westhuizen M, van Staden M, Venter C. (1998) 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; 19(3):238-44.

3) Kakar A, Beri R, Gogia A, Byotra SP, Prakash V, Kumar S, Bhargava M. (2011) Absolute lymphocyte count: a cost-effective method of monitoring HIV-infected individuals. Indian J Pathol Microbiol; 54(1):107-11.