Proceeds from website advertising help sustain Lab Tests Online. AACC is a not-for-profit organization and does not endorse non-AACC products and services.

CD4 Count

Print this article
Share this page:
Also known as: T4 Count; T-helper Cells
Formal name: CD4 Lymphocyte Count; 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 and to monitor treatment; occasionally, it may be used with other conditions (see Common Questions #4).

When to Get Tested?

When you are first diagnosed with HIV infection to get a baseline assessment of your immune system; about every 3 to 6 months after starting antiretroviral therapy (ART) to check whether you are responding to treatment; if you have responded well to treatment, you may then be tested every 6 to 12 months.

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?