HIV and Your Complete Blood Count (CBC)

If you have HIV, your healthcare provider will routinely perform blood tests to evaluate the status of your immune system (as measured by the CD4 count) and the level of viral activity in your body (as measured by the HIV viral load).

In addition to these tests, others will be performed to monitor for side effects or medical issues arising from the infection itself. Central to this is a panel of tests called the complete blood count (CBC). The test measures the composition of cells in a sample of blood to flag for changes that fall outside of the "normal" range of values.

Red and white blood cells

By doing so, a CBC can reveal if an infection is developing or if an antiretroviral drug like AZT (zidovudine) is causing anemia.

A CBC measures constituent cells in your blood, including white blood cells (leukocytes), red blood cells (erythrocytes), and platelets (thrombocytes). The test is typically ordered every three to six months but may be ordered more frequently if there is an active infection or illness.

White Blood Cell Count

White blood cells are a subset of cells produced in bone marrow whose primary role is to fight infection. A white blood cell count (WBC) is one of the panel of tests included in the CBC that measures not only the total number of leukocytes but also the different types of white blood cells in a blood sample, namely:

Within the context of HIV, an elevated WBC typically means that your body is fighting an infection. Other tests can then be performed to pinpoint the cause.

An elevation of certain white blood cells may indicate a specific type of infection or an allergic inflammatory response. For example, higher than normal eosinophils may suggest a parasitic infection like toxoplasmosis, while elevated basophils can develop in people with a hypersensitive drug reaction.

By contrast, a low WBC suggests that some condition, either HIV- or non-HIV-related, is affecting the bone marrow's ability to produce white blood cells. When this occurs, the body is less able to fight infection.

A decrease in white blood cells may be the result of HIV medications (like AZT or ganciclovir), a minor viral infection, or a major opportunistic infection like tuberculosis.

CD4 T-cell lymphocytes are a type of white blood cell that HIV preferentially targets and infects. For this reason, they serve as the primary marker of your immune status if you have HIV.

Red Blood Cell Count

Red blood cells are responsible for transporting oxygen from the lungs to cells and tissues of the body. A red blood cell count (RBC) is performed as part of the CBC to measure the total number of erythrocytes in a sample of blood along with other key values, such as:

  • Hematocrit: The percentage of blood volume taken up by red blood cells
  • Hemoglobin: The amount of protein in red blood cells responsible for carrying oxygen molecules

A low RBC is often indicative of anemia, a condition in which you lack enough healthy red blood cells to carry adequate oxygen to your body's tissues.

Within the context of HIV, anemia is known to be a common side effect of AZT. Anemia can also be due to an active infection or other causes, both HIV- and non-HIV-related.

By contrast, an abnormally high RBC, referred to as polycythemia, is less commonly associated with HIV infection. What that said, people with HIV on testosterone replacement therapy (sometimes used to treat HIV wasting or HIV-associated hypogonadism) will often experience a higher-than-normal RBC.

Platelet Count

Platelets are colorless blood cells involved in blood clotting. Platelet counts are rarely so high as to cause health problems.

By contrast, low platelet counts (thrombocytopenia) can lead to easy bleeding or bruising. Severe cases can even result in potentially life-threatening internal bleeding.

Thrombocytopenia is associated with chronic HIV infection, primarily in people with advanced disease who are not yet on treatment. With that said, in anywhere from 5% to 15% of cases, thrombocytopenia is the first sign of the disease.

The initiation of antiretroviral therapy can generally resolve the condition by suppressing the inflammatory agents that contribute to low platelet counts.

Certain HIV drugs like Fuzeon (enfuvirtide) can also cause low platelet counts, as well as opportunistic infections like cytomegalovirus (CMV) and mycobacterium avium complex (MAC).

HIV Doctor Discussion Guide

Get our printable guide for your next doctor's appointment to help you ask the right questions.

Doctor Discussion Guide Man
Was this page helpful?
10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Lab tests and why they are important. Updated February 14, 2017.

  2. U.S. Department of Health and Human Services (DHHS) Panel on Antiretroviral Guidelines for Adults and Adolescents. Table 3. Laboratory testing schedule for monitoring people with HIV before and after initiation of antiretroviral therapy. Updated December 18, 2019.

  3. Huson MA, Hoogendijk AJ, de Vos AF, Grobusch MP, van der Poll T. The impact of HIV infection on blood leukocyte responsiveness to bacterial stimulation in asymptomatic patients and patients with bloodstream infectionJ Int AIDS Soc. 2016;19(1):20759. Published 2016 May 16. doi:10.7448/IAS.19.1.20759

  4. Chou A, Serpa JA. Eosinophilia in patients infected with human immunodeficiency virus. Curr HIV/AIDS Rep. 2015 Sep;12(3):313-6. doi:10.1007/s11904-015-0272-x

  5. GlaxoSmithKline. Package insert - Retrovir (zidovudine). Updated December 2014.

  6. Meidani M, Rezaei F, Maracy MR, Avijgan M, Tayeri K. Prevalence, severity, and related factors of anemia in HIV/AIDS patientsJ Res Med Sci. 2012;17(2):138–142.

  7. Vorkas CK, Vaamonde CM, Glesby MJ. Testosterone replacement therapy and polycythemia in HIV-infected patients. AIDS. 2012 Jan 14;26(2):243-5. doi:10.1097/QAD.0b013e32834db446

  8. Ghoshal K, Bhattacharyya M. Overview of platelet physiology: Its hemostatic and nonhemostatic role in disease pathogenesisScientificWorldJournal. 2014;2014:781857. doi:10.1155/2014/781857

  9. Nascimento FG, Tanaka PY. Thrombocytopenia in HIV-infected patients. Indian J Hematol Blood Transfus. 2012 Jun;28(2):109-11. doi:10.1007/s12288-011-0124-9

  10. Prokofjeva MM, Kochetkov SN, Prassolov VS. Therapy of HIV infection: Current approaches and prospectsActa Naturae. 2016;8(4):23-32.