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CD4 T-Cell Count (Absolute)

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

This test measures the number of CD4 cells (a type of white blood cell) in your blood, which helps assess your immune system’s strength.

Quick summary

["CD4 cells are critical for fighting infections; low levels may indicate immune weakness."]

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

Key facts at a glance

LOINC
44058-6
Short code
CD4N45
Synonyms
CD4+CD45RA+CD45RB+CD45RC+ Cells # Fld
Category
chemistry
Sample
serum
Container
Sterile body fluid collection container; EDTA or heparin anticoagulant tube for blood-derived fluids
Units
N/A
Ref low
40
Ref high
70
Critical range
2 N/A – 7 N/A
Fasting
false
Population
adult
Sex
all
Age range
0–120 years
Method
Flow cytometry using fluorescently labeled monoclonal antibodies against CD4, CD45RA, CD45RB, and CD45RC surface markers
CPT
86359
SNOMED
734400006
Specimen volume
Minimum 1-5 mL of body fluid depending on source; larger volumes preferred for low-cellularity fluids
Stability
Process within 4-6 hours of collection for optimal viability. Store at room temperature (18-25°C); do not refrigerate or freeze. Cells begin to lose viability and surface marker integrity beyond 24 hours.
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your doctor may order a CD4 count to monitor immune function, especially if you have HIV, certain cancers, or other conditions affecting immunity. It’s also used to track how your immune system responds to treatment.

What Does a Low CD4 Count Mean?

A low CD4 count (typically below 200 cells per microliter) suggests a weakened immune system and may increase your risk of infections. Very low counts (below 50 cells) can lead to serious health problems.

What Does a High CD4 Count Mean?

While rare, very high CD4 counts (above 1,000 cells) may indicate overactive immune responses or certain immune disorders. Your doctor will interpret results in context with your overall health.

Sample and Testing Process

A small blood sample is drawn from your arm, usually in a doctor’s office or lab. The blood is tested to count your CD4 cells using a specialized blood test.

Reference range

Reference ranges vary by laboratory and specimen type. Naive CD4+ T-cell subsets (CD45RA+/RB+/RC+) typically comprise 40-70% of total CD4+ T cells in healthy adults. Absolute counts should be interpreted alongside total CD4+ count and clinical context.N/A

Specimen: serum

No special preparation required. Patient should be well-hydrated. Inform laboratory of current medications, especially immunosuppressive agents or recent immunizations. Avoid testing during acute infection when possible, as results may be transiently altered.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CD4 Count

Frequently asked questions

How often should I get this test?
If you have HIV, your doctor may recommend regular CD4 testing (every few months or as needed) to track your immune health and adjust medications if necessary. For others, testing may only be done if symptoms or risk factors suggest it.
What do my results mean if I’m not diagnosed with HIV?
Even without HIV, abnormal CD4 counts can signal other immune issues (e.g., autoimmune diseases, certain cancers). Always discuss results with your healthcare provider—they’ll interpret them based on your medical history.
Can I do anything to improve my CD4 count?
Yes! Maintaining a healthy lifestyle—such as eating a balanced diet, staying hydrated, avoiding smoking, and managing stress—can support immune function. If you have HIV, follow your treatment plan closely, as medications can help restore CD4 levels.
  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