CD4 Cell Count (Peripheral Blood)
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 crucial for immune function; low counts may indicate immune weakness."]
Key facts at a glance
- LOINC
- 17163-7
- Short code
- CD49a
- Synonyms
- CD49a Cells NFr Bld
- Category
- chemistry
- Sample
- whole-blood
- Container
- EDTA (lavender/purple-top) anticoagulant tube for flow cytometry; alternatively, sodium heparin (green-top) tube may be used. ACD (yellow-top) tubes are also acceptable.
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Flow cytometry using monoclonal antibodies targeting CD49a (integrin alpha-1, ITGA1) surface marker, typically performed on fresh whole blood with fluorescein (FITC) or phycoerythrin (PE) conjugated anti-CD49a antibodies; results expressed as percentage of CD49a-positive lymphocytes or absolute cell count per unit volume
- CPT
- 86356 (for flow cytometry, cell surface marker, technical component only; additional CPT codes may apply based on panel composition)
- SNOMED
- 116849008 (Cell surface marker measurement)
- Specimen volume
- 3-5 mL of whole blood in EDTA tube; minimum 1 mL required for pediatric samples. For absolute counts, a CBC with differential should be performed concurrently.
- Stability
- Specimen should be processed within 24 hours of collection when stored at room temperature (18-25°C). If delayed, samples may be stored at 2-8°C for up to 48 hours; however, viability and marker expression may decline. Do not freeze whole blood samples.
- Hemolysis max
- 100
- Lipemia max
- 500
- Icterus max
- 20
- TAT
- 24–72 hours
- Order
- routine
Why This Test Matters
CD4 cells are a key part of your immune system. They help your body fight off infections like viruses, bacteria, and fungi. Low CD4 counts can signal weakened immunity, especially in conditions like HIV or certain autoimmune diseases.
How the Test Works
Blood is drawn from a vein, typically in your arm. The sample is analyzed to count CD4 cells using a specialized blood test that identifies these immune cells.
What to Expect Before or After
No special preparation is needed, but avoid vigorous exercise or eating heavy meals 1 hour before your appointment. After the draw, you may feel slight bruising or discomfort at the site, which usually fades quickly.
Common Reasons for Testing
Doctors may order this test to monitor immune health, diagnose conditions like HIV, track treatment progress, or check for immune deficiencies.
Reference range
Reference ranges for CD49a+ cells in peripheral blood are not well established and may vary significantly by laboratory. Generally, CD49a expression on peripheral blood lymphocytes is low under normal conditions; reported ranges typically fall between 0.1% and 2.5% of total lymphocytes. Results should always be interpreted in conjunction with clinical context and laboratory-specific reference intervals.N/A
No special fasting or dietary restrictions are required. Patients should inform their healthcare provider of any recent infections, vaccinations, immunosuppressive therapies, or medications that may alter immune cell populations. Avoid scheduling the test during acute illness when possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
CD4 T-Cell Count
Frequently asked questions
Low CD4 counts below a certain threshold (varies by individual and clinical context) may indicate immune suppression, requiring closer monitoring or treatment adjustments. High counts may suggest normal or overactive immune function, but further evaluation is needed if symptoms persist.
Your results will be discussed with your healthcare provider, who will explain what they mean in the context of your health. They may recommend follow-up testing or adjustments to your treatment plan.
Yes, you can ask your doctor to review your CD4 count alongside other lab results, such as viral load (for HIV) or other immune markers.
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 15, 2026. · Read our editorial policy