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CD4 Count

Published: July 27, 2026Updated: August 25, 2026

The CD4 count measures the number of CD4 T-helper cells in a microliter of blood, which are crucial for the immune system's response to infections.

Quick summary

CD4 count indicates the health of the immune system and is vital for diagnosing and managing HIV/AIDS.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
cells/μL
Clinical utility
diagnostic
Result kind
quantitative
FDA-cleared
BD FACSCanto CD4, Abbott CD4, Beckman Coulter CD4
interpretation: {"text":"A CD4 count below 500 cells/μL may indicate immunodeficiency, often associated with HIV/AIDS.","label":"Low CD4 Count"}; {"text":"A CD4 count above 1500 cells/μL is less common and may require further investigation for other immune disorders.","label":"High CD4 Count"}

CD4 cells, also known as T-helper cells, play a critical role in orchestrating the immune response to pathogens. The CD4 count is a direct measure of the number of these cells in a microliter of blood.

A normal CD4 count ranges from 500 to 1500 cells/μL. A count below 500 cells/μL may indicate a weakened immune system, often seen in HIV/AIDS patients.

Regular monitoring of CD4 counts is essential for assessing the progression of HIV infection and the effectiveness of antiretroviral therapy.

Frequently asked questions

What is a normal CD4 count?
A normal CD4 count ranges from 500 to 1500 cells/μL.
Why is CD4 count important in HIV patients?
CD4 count is crucial for monitoring the immune system's health and the effectiveness of HIV treatment.
  1. 1
    CDC - Understanding CD4 Cells and CD4 CountsSource
  2. 2
    World Health Organization - HIV/AIDSSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy