CD4 Lymphocyte Count

What Is a CD4 Lymphocyte Count?

A CD4 lymphocyte count is a laboratory test used to measure the amount of CD4 lymphocytes, which are one type of white blood cell, in a sample of blood. CD4 lymphocytes are also known as T-helper cells and play a major role in the body’s immune response.

Preparation for a CD4 Lymphocyte Count

No preparation is needed for this test. There is no need to fast or stop taking any medications.

Procedure of a CD4 Lymphocyte Count

A health care provider will take a small sample of blood, usually from a vein in the arm. The sample will be sent to a laboratory for analysis.

Types of CD4 Lymphocyte Counts

There are two types of CD4 lymphocyte counts:

  • Absolute CD4 count: This test measures the absolute number of CD4 lymphocytes in a given sample of blood.
  • CD4 percentage: This test measures the percentage of CD4 lymphocytes relative to other types of white blood cells in a given sample of blood.

Risks of a CD4 Lymphocyte Count

Risks associated with the CD4 lymphocyte count are generally minor. They may include bleeding, infection, and bruising. These risks are generally related to taking the blood sample, and not to the test itself.

Why Do CD4 Lymphocyte Counts Matter?

CD4 lymphocyte counts are an important measure of a person's immune system health. Low CD4 counts can indicate diseases such as HIV, while high counts can represent infection and inflammation. CD4 counts are also used to track the effectiveness of HIV treatments.

When to Take a CD4 Lymphocyte Count?

A CD4 lymphocyte count is typically ordered for people with HIV and for other people with weakened immune systems. It may also be used to monitor people for whom regular HIV treatments may not be appropriate and to assess any side effects of certain medications.