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Lymphocyte count (serum/plasma mass concentration)

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

This test measures the number of lymphocytes, a type of white blood cell that plays a key role in your immune system. Lymphocytes help fight infections and diseases.

Quick summary

["Your immune health depends on balanced white blood cell counts, including lymphocytes."]

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

Key facts at a glance

LOINC
33642-0
Short code
Lymphocyte Ab Ser FC-aCnc
Synonyms
Lymphocyte Ab Ser FC-aCnc
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
CPT
86430
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 healthcare provider may order this test to check for infections, immune system disorders, or conditions affecting your white blood cell count, such as leukemia, lymphoma, or autoimmune diseases. It may also be used to monitor treatment responses or evaluate symptoms like frequent infections, fatigue, or unexplained weight loss.

What to Expect Before the Test

No special preparation is usually needed. You may have a blood draw from a vein in your arm. If you’re on blood-thinning medication, let your provider know to avoid unnecessary risks.

What the Results Mean

Results are typically reported as a count of lymphocytes per microliter (cells/µL) of blood. Abnormal results may indicate low (lymphopenia) or high (lymphocytosis) lymphocyte levels, which can signal underlying health concerns.

Common Conditions Linked to Results

Low lymphocyte counts may suggest immune deficiencies, infections, or certain medications. High counts could indicate chronic infections, inflammation, or overactive immune responses. Always discuss results with your provider for personalized interpretation.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Lymphocyte Level

Frequently asked questions

How often will I need this test?
Frequency depends on your health status and treatment plan. Some people need this test regularly to monitor chronic conditions or after receiving immune-modifying treatments.
Can I eat or drink before the test?
Typically, fasting is not required, but follow your provider’s instructions. Avoid heavy meals or alcohol before blood draws to ensure accurate results.
What if my results are outside the normal range?
Your provider will explain what the results mean in the context of your health. They may recommend further testing, lifestyle adjustments, or treatments based on the findings.
  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