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CD4 T-Cell Count (with CD4/CD8 Ratio)

Published: August 9, 2026Updated: August 17, 2026

This test measures the number of CD4+ T-cells (a type of white blood cell) in your blood and the ratio of CD4 to CD8 T-cells, which helps assess immune function and monitor conditions like HIV.

Quick summary

["Measures immune health and HIV progression by tracking T-cell counts and ratios."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
44060-2
Short code
CD4NVE
Synonyms
CD4+CD45RA+CD45RB+CD45RC+ Cells # Spec
Category
chemistry
Sample
serum
Container
EDTA (lavender-top) or ACD (yellow-top) anticoagulated blood collection tube for flow cytometry; heparinized tubes may be used for some protocols
Units
N/A
Ref low
500
Ref high
1500
Critical range
2 N/A – 7 N/A
Fasting
false
Population
adult
Sex
all
Age range
0–99 years
Method
Flow cytometry using fluorescently labeled monoclonal antibodies against CD4, CD45RA, CD45RB, and CD45RC surface markers; results expressed as absolute count per unit volume
CPT
86360
SNOMED
249200007
Specimen volume
3-5 mL whole blood for adults; minimum 1 mL for pediatric patients
Stability
Specimen should be processed within 24-30 hours of collection when stored at room temperature (18-25°C). Do not refrigerate or freeze whole blood samples. Lymphocyte viability declines significantly beyond 48 hours.
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Matters

CD4+ T-cells are critical for fighting infections and maintaining immunity. Low counts can indicate weakened immunity, while the CD4/CD8 ratio helps doctors evaluate immune balance, especially in conditions like HIV or autoimmune diseases.

What to Expect Before the Test

No special preparation is needed, but you may be asked to fast for 8–12 hours if blood is drawn from a vein. Bring any medications or supplements you’re taking, as they may affect results.

How the Test Works

Blood is drawn from a vein (usually in your arm) and analyzed to count CD4+ T-cells and calculate the CD4/CD8 ratio. The test uses advanced technology to detect and quantify these immune cells.

Common Uses for This Test

This test is often used to diagnose or monitor HIV, track immune recovery in cancer patients undergoing treatment, or evaluate autoimmune diseases. It helps doctors guide treatment plans.

Reference range

Reference ranges vary by laboratory and patient population; adult peripheral blood CD4+ T-cell absolute counts typically range from 500-1500 cells/µL (0.5-1.5 x 10^9/L). Naive CD4+ T-cells (CD45RA+RB+RC+) typically represent 20-60% of total CD4+ T-cells. Pediatric reference ranges differ substantially and should be interpreted using age-appropriate reference data.N/A

Specimen: serum

No special preparation required. Specimen should ideally be processed within 24 hours of collection to maintain cell viability. Avoid stressful exercise prior to collection as it may transiently alter lymphocyte subset distribution.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical significance: Low CD4 counts (below 200 cells/mm³) often signal immune deficiency, increasing infection risk. The CD4/CD8 ratio may also reveal immune dysfunction, guiding decisions for HIV treatment or other conditions like rheumatoid arthritis.

Short name

CD4 Count & Ratio Test

Frequently asked questions

What does a low CD4 count mean?
A low CD4 count (typically below 500 cells/mm³) suggests a weakened immune system. This can happen with HIV, chemotherapy, or other immune disorders. Your doctor will discuss next steps based on your overall health.
Does fasting affect this test?
No, fasting is not required for this test. However, if you’re taking medications that affect blood cells, let your doctor know—it may influence results.
How often should I get this test?
Frequency depends on your health condition. For HIV, tests may be done every 3–6 months. Your doctor will schedule follow-ups based on your treatment plan and lab results.
  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 17, 2026. · Read our editorial policy