CD4 T-Cell Count (with CD4/CD8 Ratio and CD4+ Memory T-Cell Subset Analysis)
This blood test measures the number of CD4 T-cells (a type of immune cell) and evaluates their relationship with CD8 T-cells, along with a subset of memory T-cells. It helps assess immune function and monitor conditions like HIV.
["CD4 T-cells are critical for fighting infections and maintaining immunity; low counts may signal immune weakness."]
Key facts at a glance
- LOINC
- 44057-8
- Short code
- CD4NAIVE
- Synonyms
- CD4+CD45RA+CD45RB+CD45RC+ Cells # CSF
- Category
- chemistry
- Sample
- csf
- Container
- Sterile CSF collection tube (polypropylene), tube 3 or 4 preferred for cell-based analysis to minimize blood contamination
- Units
- N/A
- Ref low
- 4.2
- Ref high
- 5.9
- Critical range
- 2 N/A – 7 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Flow cytometry
- CPT
- 86356
- SNOMED
- 121006009
- Specimen volume
- 1-3 mL of cerebrospinal fluid; minimum 0.5 mL required for flow cytometry immunophenotyping
- Stability
- Process within 1-2 hours of collection; if delay is anticipated, refrigerate at 2-8°C and process within 4 hours. Do not freeze.
- Hemolysis max
- 200
- TAT
- 4–24 hours
- Order
- routine
Why This Test Matters for Your Health
CD4 T-cells are a key part of your immune system. They help your body fight off infections and diseases. This test helps doctors track how well your immune system is working, especially if you have HIV or another condition that affects your immune cells.
What the Test Measures
The test includes three main measurements: the absolute count of CD4 T-cells, the ratio of CD4 to CD8 T-cells, and the percentage of CD4+ memory T-cells. These numbers help determine immune health and guide treatment decisions.
How the Test Is Performed
A small blood sample is drawn from your arm. The blood is then analyzed in a lab to count CD4 and CD8 T-cells and assess memory T-cell subsets using advanced immune testing methods.
What Your Results Mean
Lower CD4 counts or abnormal ratios may indicate immune suppression, which can increase your risk of infections or diseases. Higher CD4 counts or normal ratios suggest a stronger immune response. Your doctor will interpret these results in the context of your overall health.
Reference range
Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A
No special patient preparation required. Inform the ordering physician of any recent immunosuppressive therapy or immunomodulatory treatments.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
CD4 Cell Test
Frequently asked questions
What does a low CD4 count mean?
How does the CD4/CD8 ratio help doctors?
Why is the CD4+ memory T-cell subset important?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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 17, 2026. · Read our editorial policy