CD4 T-Cell Count (Absolute)
This test measures the number of CD4 cells (a type of white blood cell) in your blood. CD4 cells help your immune system fight infections.
["CD4 cells are key to your immune health; lower counts may signal immune weakness."]
Key facts at a glance
- LOINC
- 38240-8
- Short code
- CD4CD95
- Synonyms
- CD4+CD95+ Cells NFr Bld
- Category
- chemistry
- Sample
- whole-blood
- Container
- EDTA (lavender/purple-top) vacuum blood collection tube, preferably ACD-A (yellow-top) for optimal cell viability in flow cytometry; sodium heparin (green-top) is an acceptable alternative for some platforms
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Flow cytometry using fluorescently labeled monoclonal antibodies against CD4 and CD95 surface markers, with leukocyte gating and CD45/SSC lympho-gating strategy for subset enumeration
- CPT
- 86359
- SNOMED
- 405365004
- Specimen volume
- 1-3 mL of whole blood for adults; minimum 0.5-1 mL for pediatric patients
- Stability
- Process within 4-6 hours of collection at room temperature (18-22°C) for optimal lymphocyte viability. Refrigerated storage (2-8°C) acceptable for up to 24 hours but may affect some surface markers. Do not freeze whole blood samples.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
Why This Test Is Done
Your doctor may order this test to monitor your immune system, especially if you have HIV, certain cancers, or conditions like HIV/AIDS. It helps track how well your immune system is responding to treatment or managing a health condition.
What to Expect Before the Test
No special preparation is needed. You’ll have a small needle inserted into your arm or hand to draw a blood sample. The process usually takes a few minutes, and you may feel a brief pinch.
What the Results Mean
Results show your absolute count of CD4 cells per microliter (µL) of blood. Lower counts may indicate immune suppression, while higher counts suggest a stronger immune response. Your doctor will interpret results based on your health history and medical needs.
Common Causes of Abnormal Results
Low CD4 counts can occur due to infections (like HIV), certain medications, or chronic illnesses. High counts may be normal or linked to conditions like autoimmune disorders or infections.
Reference range
Reference ranges are laboratory-specific and vary based on instrumentation, antibody clones, and gating strategies. Generally reported as either cells/μL or percentage of total lymphocytes. CD4+CD95+ cells represent activated/sensitized helper T lymphocytes.N/A
No special preparation required. Patient should be well-hydrated. Inform laboratory of any recent corticosteroid therapy, chemotherapy, or immunosuppressive medications, as these may affect results. For serial monitoring, collect samples at consistent time of day.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
CD4 Cell Count
Frequently asked questions
What does a CD4 cell count measure?
How is this test different from HIV testing?
Can diet or exercise affect CD4 cell counts?
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 16, 2026. · Read our editorial policy