Activtlymphsnfrbld
A blood test that measures the number of activated T cells (a type of white blood cell) to evaluate how well your immune system is functioning.
{"This test measures activated T lymphocytes in your blood, which are crucial for fighting infections","It helps doctors diagnose and monitor conditions like HIV, leukemia, and immune system disorders","A small blood sample is taken from a vein in your arm for analysis","Results are compared with normal ranges to determine if your immune system is functioning properly","Abnormal results may indicate infection, autoimmune disease, or other health conditions"}
Key facts at a glance
- LOINC
- 20631-8
- Short code
- Activated T cells
- Synonyms
- Activ T Lymphs NFr Bld
- Category
- chemistry
- Sample
- whole-blood
- Container
- EDTA tube (Lavender top, 4 mL vacuum tube)
- Units
- N/A
- Ref low
- 5
- Ref high
- 30
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Flow Cytometry Immunophenotyping
- CPT
- 86355
- SNOMED
- 122275009
- Specimen volume
- 3-5 mL of whole blood
- Stability
- Room temperature (20-25°C): Process within 24-48 hours. Do not refrigerate. Keep upright.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 24–72 hours
- Order
- routine
What is this test?
The Activated T Cell Count test measures the number of activated T lymphocytes (a type of white blood cell) in your bloodstream. T cells are a crucial part of your immune system that help protect your body against infections and diseases. When T cells encounter foreign substances like viruses or bacteria, they become 'activated' and begin to fight off the invader.
Why do I need this test?
Your doctor may order this test to: evaluate how your immune system is functioning; diagnose or monitor conditions such as HIV/AIDS, leukemia, or lymphoma; check for autoimmune disorders; monitor the effects of medications that affect the immune system (like chemotherapy or immunosuppressants); or investigate unexplained symptoms such as persistent infections, fatigue, or fever.
How is the test performed?
A healthcare professional will draw a small sample of blood from a vein in your arm using a needle. The blood sample is then sent to a laboratory where specialists analyze it to determine the number and percentage of activated T cells. The procedure only takes a few minutes and is generally well-tolerated.
How should I prepare?
No special preparation is typically required for this test. You can eat and drink normally before the blood draw. However, always follow any specific instructions given by your healthcare provider. Inform your doctor about all medications you are taking, as some drugs may affect test results.
Reference range
Activated T cells (CD3+CD25+ or HLA-DR+): 5-30% of total lymphocytes or 50-400 cells/μL. Reference ranges may vary by laboratory and specific antibody panel used.N/A
No special preparation required. Patient may eat and drink normally before sample collection.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Frequently asked questions
Are there any risks with this test?
How long does it take to get results?
What do abnormal results mean?
Do I need to fast before this test?
Sources
- 1
- 2
- 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