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Lymphocyte count (manual differential blood count)

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

This test measures the types and proportions of white blood cells called lymphocytes in your blood, often done manually for detailed analysis. It helps assess immune function and identify potential infections or disorders.

Quick summary

["Understanding your lymphocyte breakdown can guide treatment for immune-related conditions."]

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

Key facts at a glance

LOINC
71649-8
Short code
Lymphocytes NFr.DF Fld Manual
Synonyms
Lymphocytes NFr.DF Fld Manual
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
manual-count
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 Is Done

Doctors may order a lymphocyte differential when they suspect conditions like infections (e.g., viral or bacterial), autoimmune diseases, or certain cancers. It can also help monitor immune responses to treatments or track chronic conditions like leukemia.

What to Expect Before the Test

No special preparation is needed. You’ll have a small needle inserted into your arm or hand to draw blood. If you’re nervous, ask your doctor about ways to stay calm during the procedure.

How the Results Are Interpreted

Results show the percentage of different lymphocyte types (e.g., T cells, B cells, natural killer cells). While reference ranges vary by lab, abnormal proportions may signal immune dysfunction or disease.

Common Conditions Linked to Lymphocyte Findings

Low lymphocyte counts might indicate immune suppression (e.g., HIV/AIDS, chemotherapy), while high counts could signal chronic infections or overactive immune responses (e.g., lymphoma).

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Lymphocyte Differential

Frequently asked questions

How often should I get this test?
This test is typically done as needed based on symptoms or medical concerns. Your doctor will determine frequency based on your diagnosis or treatment plan.
What does it mean if my lymphocyte count is high or low?
High counts may suggest chronic infections, autoimmune disorders, or certain cancers. Low counts could indicate immune weakness, side effects of treatment, or genetic conditions. Always discuss results with your healthcare provider.
Can lifestyle changes affect lymphocyte counts?
While diet, stress, and sleep can influence immune function, they don’t directly alter lymphocyte differentials. Focus on maintaining overall health to support immune balance.
  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