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CD4 T-Cell Count (from Whole Blood)

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

This test measures the number of CD4 cells (a type of white blood cell) in your blood. CD4 cells play a key role in helping your immune system fight infections.

Quick summary

["CD4 cells help your body defend against infections and diseases; low levels may indicate immune weakness."]

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

Key facts at a glance

LOINC
38239-0
Short code
CD4CD95
Synonyms
CD4+CD95+ Cells # Bld
Category
chemistry
Sample
whole-blood
Container
EDTA (lavender/purple-top) blood collection tube for flow cytometry; sodium heparin (green-top) tube is also acceptable for immunophenotyping
Units
N/A
Ref low
500
Ref high
1500
Critical range
200 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 (Fas/APO-1) surface markers, with absolute counting performed using fluorescent beads or volumetric measurement
CPT
86359 (T cells, total count); 86360 (T cells, CD4 absolute count); additional markers may be billed under 86361 or unlisted code
SNOMED
39089005 |CD4-positive T-lymphocyte (cell)| ; 27355003 |Lymphocyte (cell)|
Specimen volume
3-5 mL of whole blood; minimum 1 mL for pediatric samples
Stability
Process within 24-30 hours of collection when stored at room temperature (18-25°C). Refrigeration at 2-8°C may reduce viability and surface marker expression. Do not freeze whole blood specimens.
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
24–72 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order a CD4 count to monitor your immune system, especially if you have HIV/AIDS, certain cancers, or other conditions that affect immune function. It can also help track how well treatments are working or if your immune system is recovering.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm or hand to draw a blood sample. The process usually takes a few minutes, and you’ll feel a brief pinch. If you’re nervous, let your provider know—some people use numbing cream or choose a different vein.

What Happens During the Test?

The blood sample is sent to a lab where it’s analyzed to count your CD4 cells. The test doesn’t involve radiation or invasive procedures beyond the blood draw. Results are typically available within a few days.

What the Results Mean

CD4 counts are often reported as a number (e.g., 200 cells per microliter). Lower counts may signal immune suppression, while higher counts suggest a stronger immune response. Your provider will interpret results in the context of your overall health and medical history.

Reference range

Reference ranges vary by laboratory and instrumentation. Typical adult values: CD4+ T cells 500-1500 cells/μL; CD95+ expression on CD4+ cells approximately 20-70% of CD4+ T cells. Absolute CD4+CD95+ count is method- and population-dependent; consult local laboratory reference interval.N/A

Specimen: whole-blood

No special patient preparation required. Fasting is not necessary. Patients should be well-hydrated. Recent vaccinations, infections, immunosuppressive therapy, or stress may transiently alter lymphocyte subset populations and should be documented.

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?
A low CD4 count may indicate your immune system is not functioning as well as it should, which can raise the risk of infections or other health issues. Your provider will discuss your results with you and explain what they mean for your care plan.
How often should I get this test?
The frequency depends on your health condition. If you have HIV, your provider may recommend regular testing to track your immune status and adjust treatments. Others may only need it if they have symptoms of immune problems or are at higher risk.
Can I eat or drink before this test?
You can eat and drink normally before this test, as it doesn’t require fasting. However, let your provider know if you’re on blood-thinning medications or have any concerns about the blood draw.
  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