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Lymphocyte count (manual differential blood count)

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

This test measures the number of lymphocytes, a type of white blood cell, in your blood. Lymphocytes help fight infections and maintain immunity.

Quick summary

["Lymphocytes are key to your immune system; this test helps track their levels for health monitoring."]

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

Key facts at a glance

LOINC
737-7
Short code
Lymphocytes NFr Bld Manual
Synonyms
Lymphocytes NFr Bld Manual
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
manual-count
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why is this test done?

Your healthcare provider may order this test to check for infections, immune system disorders, or conditions like leukemia, lymphoma, or autoimmune diseases. It can also help monitor treatment progress for certain conditions.

What does the test involve?

A small blood sample is drawn from a vein, usually in your arm. The sample is then examined under a microscope by a trained technician to count and identify different types of white blood cells, including lymphocytes.

What should you do before the test?

No special preparation is needed for this test. However, inform your healthcare provider about any medications you’re taking or recent illnesses, as they may affect your results.

What are the results typically used for?

Results help determine if your immune system is functioning normally or if there’s an imbalance that needs further investigation. Elevated or low lymphocyte counts may signal underlying health concerns.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical significance: Lymphocyte counts can indicate immune function, infection risk, or certain diseases. High levels may suggest chronic infections, immune disorders, or certain cancers, while low levels could point to immune deficiencies, severe infections, or treatments like chemotherapy.

Short name

Lymphocyte count

Frequently asked questions

How long does it take to get results?
Results are typically available within a few hours to a couple of days, depending on lab processing times and whether additional testing is needed.
Can I eat or drink before this test?
You can eat and drink normally before this test unless instructed otherwise by your healthcare provider.
Is there any discomfort during the test?
You may feel a slight pinch when the needle is inserted, but the procedure is usually quick and well-tolerated. Most people experience minimal discomfort afterward.
  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