Lymphocyte Count (Manual Blood Cell Differential)
This test measures the number of lymphocytes, a type of white blood cell that plays a key role in fighting infections and maintaining immune function.
["Lymphocytes help your body defend against illness and disease."]
Key facts at a glance
- LOINC
- 78355-5
- Short code
- Lymph Abn Bld Ql Manual
- Synonyms
- Lymph Abn Bld Ql 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 This Test Might Be Ordered
Your healthcare provider may order this test to evaluate your immune system, diagnose conditions like infections, autoimmune diseases, or certain cancers, or to monitor treatment progress. It can also help identify conditions affecting white blood cell counts, such as leukemia or lymphomas.
What to Expect Before the Test
No special preparation is typically needed. You may be asked to fast before the test if it involves drawing blood, but this is not always the case for a manual differential. Bring any medications or questions to your appointment.
How the Test Is Performed
A healthcare professional will take a small sample of blood from a vein in your arm using a needle. The blood is then examined under a microscope by a trained technician to count and identify different types of white blood cells, including lymphocytes.
What the Results Mean
Results are usually reported as a count of lymphocytes per microliter (µL) of blood. While specific reference ranges can vary by lab, lower than expected counts may suggest immune deficiencies or infections, while higher counts might indicate chronic inflammation, certain infections, or other conditions.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Lymphocyte counts are crucial for diagnosing and managing a variety of health conditions. Low lymphocyte counts can signal immune system dysfunction, which may be due to conditions like HIV/AIDS, chemotherapy, or autoimmune diseases. High lymphocyte counts can be seen in chronic infections, certain cancers, or inflammatory disorders. Monitoring lymphocyte counts helps guide treatment decisions and assess the effectiveness of therapies.
Short name
Lymphocyte Count
Frequently asked questions
What causes a low lymphocyte count?
What causes a high lymphocyte count?
How often should I get this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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