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Total T-Cell Count (Peripheral Blood)

Published: August 9, 2026Updated: August 16, 2026

This test measures the total number of T-cells in your blood, which are a type of white blood cell important for immune function.

Quick summary

["T-cells help your body fight infections and detect cancer cells."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
52998-2
Short code
TdT Cells NFr Tiss FC
Synonyms
TdT Cells NFr Tiss FC
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
flow-cytometry
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your doctor may order this test if you have symptoms of a weakened immune system, such as frequent infections, unexplained weight loss, or fatigue. It could also be part of a routine check-up for conditions like HIV, autoimmune diseases, or cancer.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast before the test, but this is often not required for a blood draw. Bring any medications you’re currently taking to your appointment.

How the Test Works

A small amount of blood is drawn from a vein in your arm. The blood sample is then analyzed to count the total number of T-cells in your circulation.

What the Results Mean

Results are typically reported as a count of T-cells per microliter (µL) of blood. Lower than expected counts may indicate immune deficiencies or certain diseases, while higher counts might suggest inflammation or other conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

T-Cell Count

Frequently asked questions

What causes a low T-cell count?
Low T-cell counts can result from conditions like HIV infection, certain cancers (e.g., lymphoma), autoimmune diseases, long-term use of certain medications (e.g., steroids), or severe infections.
What causes a high T-cell count?
High T-cell counts may be due to chronic infections, autoimmune disorders, or certain cancers. They can also appear in response to inflammation or as part of a normal immune response to an infection.
How often should I get this test?
The frequency depends on your health condition and doctor’s recommendations. For example, HIV patients may need regular monitoring, while others may only need it if symptoms arise or as part of routine care.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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