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CD4 and CD8

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Also known as: T4 Count; T-helper Cells; T-suppressor Cells; Cytotoxic T-cells
Formal name: CD4 Lymphocyte Count; CD8 Lymphocyte Count; CD4/CD8 Ratio; CD4 Percent

At a Glance

Why Get Tested?

Most often, this test is done to measure the strength of your immune system if you have been diagnosed with human immunodeficiency virus (HIV) infection; occasionally, it may be used with other conditions (see Common Questions #4).

When to Get Tested?

When you have been diagnosed with HIV, soon after you are first diagnosed to get a baseline assessment of your immune system; 2-8 weeks after starting anti-HIV therapy and then every three to four months as you continue therapy

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?