CD4 T-Cell Count (Per Microliter) in Whole Blood
This test measures the number of CD4 cells (a type of white blood cell) in your blood. CD4 cells help fight infections and are important for immune function.
["CD4 cells are a key marker of your immune system’s strength."]
Key facts at a glance
- LOINC
- 80223-1
- Short code
- CD4
- Synonyms
- CD4 Cells/lymph NFr Spec
- Category
- chemistry
- Sample
- serum
- Container
- EDTA (lavender/purple-top) tube for flow cytometry; alternatively, sodium heparin (green-top) tube
- Units
- N/A
- Ref low
- 500
- Ref high
- 1500
- Critical range
- 200 N/A – —
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–99 years
- Method
- Flow cytometry using fluorescently labeled monoclonal antibodies against CD4 surface markers; results reported as percentage and absolute count of CD4+ T lymphocytes
- CPT
- 86359
- SNOMED
- 395142008
- Specimen volume
- 3-5 mL whole blood (adults); 1-3 mL (pediatric); minimum 1 mL for flow cytometry analysis
- Stability
- Ambient temperature: 24 hours; Refrigerated (2-8°C): 48 hours. Do not freeze. Specimen should be processed within 30 hours of collection for optimal lymphocyte viability and accurate CD4 enumeration.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why Is This Test Done?
Your doctor may order this test to monitor your immune system, especially if you have HIV/AIDS, certain cancers, or other conditions that weaken immunity. It helps track how well your immune system is responding to treatment or disease progression.
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 is quick and usually painless. If you’re nervous, let your healthcare provider know.
What the Results Mean
Results are typically reported as a count of CD4 cells per microliter (µL) of blood. Lower counts may indicate a weakened immune system, while higher counts suggest a stronger immune response. Your doctor will interpret results in the context of your overall health.
Common Reasons for Testing
This test is often used to diagnose or manage conditions like HIV infection, certain cancers (e.g., lymphoma), or immune deficiencies. It’s also part of routine monitoring for people with chronic illnesses.
Reference range
Absolute CD4 count: 500-1500 cells/μL (adults); CD4 percentage: 40-70% of total lymphocytes. Pediatric ranges vary by age.N/A
No fasting required. Patient should be well-hydrated. Avoid strenuous exercise prior to collection. For serial monitoring, specimen should ideally be collected at the same time of day to minimize diurnal variation. Recent vaccinations, infections, or immunosuppressive therapies may affect results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
CD4 Count
Frequently asked questions
What Does a Low CD4 Count Mean?
How Often Should I Get This Test?
Can Diet or Supplements Affect CD4 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