Differential Leukocyte Count
Understanding Differential Leukocyte Count
What is Differential Leukocyte Count?
The Differential Leukocyte Count test measures the percentage of each type of leukocyte or white blood cell (WBC) in the blood. This test is a key indicator of WBC abnormalities, such as infections, inflammation, allergies, bone marrow disorders, or autoimmune diseases. It is also done as part of a complete blood count test that also measures other types of blood cells.
Leukocytes or WBCs are a crucial part of the immune system and play a vital role in protecting the body from infections and diseases. The DLC test provides information about the percentage of each type of white blood cell, including neutrophils, lymphocytes, monocytes, eosinophils, and basophils, as each supports the immune system differently. An analysis of the distribution of these white blood cells gives insights into the body's immune response.
Certain infections or medical conditions may cause specific types of white blood cells to increase or decrease. This alteration can help diagnose and monitor various health issues, such as infections, allergies, inflammation, or certain blood disorders. A decrease in the WBC count, also known as leukopenia, leads to a decline in the body's ability to fight infections. On the other hand, an increase in the WBC count, known as leukocytosis, indicates acute infections and inflammation. However, the Differential Leukocyte Count test may require follow-up tests to determine the exact cause of the abnormal results. Usually, no special preparation is needed for this test; you can eat or drink as per your daily routine.
Test result ranges are approximate and may differ slightly between labs depending on the methodology and laboratory guidelines. Talk to your doctor about your specific test results. The results will help them determine your overall health and immune system function and suggest appropriate treatments when necessary.
What is Differential Leukocyte Count used for?
The Differential Leukocyte Count test can be done:
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As part of routine checkups to monitor your overall health.
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As part of a (CBC) complete blood count test.
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To detect infection, inflammation, and allergies.
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To detect white blood cell disorders, such as leukopenia, leukocytosis, or leukemia.
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To detect bone marrow disorders affecting WBC count.
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To monitor bone marrow function.
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To monitor treatments affecting the number of WBCs, such as chemotherapy or radiotherapy.
What does Differential Leukocyte Count measure?
Contains 5 testsThere are five types of WBCs: neutrophils, lymphocytes, monocytes, eosinophils, and basophils. A Differential Leukocyte Count test measures the percentage of each type of WBC in the blood. Leukocytes or WBCs are produced in the bone marrow and defend the body against infections and diseases. Each type of WBC plays a unique role to protect against infections and is present in different numbers.
Differential Basophil Count
The Differential Basophil Count test measures the relative percentage of basophils in the blood. Basophils are spherically shaped small cells that originate from bone marrow and make up almost 1% of the total white blood cells in the body. These cells attack a foreign substance and release proteins, like histamine and heparin, to destroy harmful substances like allergens, pathogens, or parasites. Histamine helps widen the blood vessels and make space for more immune cells to come to the site of infection or injury, whereas heparin acts as a blood-thinning agent and helps avoid blood clotting at the infection or injury site.
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Differential Neutrophil Count
The Differential Neutrophil Count test measures the total percentage of neutrophils in the blood. This test helps your doctor determine the underlying cause of symptoms like fever, inflammation, or infection by identifying the type of infection, i.e., bacterial or viral.
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Differential Lymphocyte Count
The Differential Lymphocyte Count test measures the proportion of different types of lymphocytes in the blood. Lymphocytes are a type of white blood cells that play an important role in the functioning of your immune system, which helps your body fight disease and infection.
There are two main types of lymphocytes:
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T lymphocytes (T cells): T cells control your body’s immune system response and directly attack and kill infected cells and tumor cells.
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B lymphocytes (B cells): B cells make antibodies. Antibodies are proteins that target viruses, bacteria, and other foreign invaders.
Lymphocytes help your immune system remember every antigen (a foreign substance) it comes in contact with. After an encounter, some lymphocytes turn into memory cells. When these memory cells run into an antigen again, they recognize it and quickly respond. It is also the reason why getting vaccinated can help prevent certain diseases.
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Differential Monocyte Count
A Differential Monocyte Count test measures the relative percentage of monocytes in the blood.
Monocytes are the type of white blood cells that originate from bone marrow and travel to different tissues via blood. Once they are inside the tissue, they get converted into macrophages (a type of cell that digests harmful substances). These cells are the second line of defense in the human body after neutrophils. Monocytes are responsible for the removal of injured or dead cells, microorganisms, and other insoluble particles from the blood.
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Differential Eosinophil Count
The Differential Eosinophil Count test measures the proportion of eosinophils in relation to other types of white blood cells (WBC), such as neutrophils, lymphocytes, basophils, and monocytes. Eosinophils originate from bone marrow and have a lifespan of 8-18 hours. These cells are involved in fighting certain types of infections and responding to allergic reactions in the body. The eosinophils have varied functions that include the physiological role in organ formation, such as the development of post-gestational mammary glands. Other functions include its movement to the areas of inflammation, trapping the substances, and killing the cells with bactericidal and antiparasitic activities. It also helps in the treatment of immediate allergic reactions and modulation of inflammatory responses.
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Interpreting Differential Leukocyte Count results
Interpretations
Normal range (Approx.):
|
Component |
Mean number fraction |
Absolute counts X 109 per liter |
|
Segmented Neutrophils |
0.56 |
1.8-7.8 |
|
Eosinophils |
0.027 |
0-0.45 |
|
Basophils |
0.003 |
0-0.20 |
|
Lymphocytes |
0.34 |
1.0-4.8 |
|
Monocytes |
0.04 |
0-0.80 |
Note: Normal range of leukocyte count depends on several factors apart from age, including gender, health condition, previous instance of diseases, vaccinations, etc. The range also varies slightly between different laboratories performing the test.
The results of the differential leukocyte count may be interpreted in combination with other tests as follows:
|
Type of WBC |
Conditions causing higher than normal count |
Conditions causing lower-than-normal count |
|
Neutrophils |
Known as neutrophilia · Acute infections, mostly bacterial, and in some cases viral or fungal · Inflammatory conditions like rheumatoid arthritis · Necrosis (tissue death) caused by burns, trauma, surgery, heart attack, etc. · Heavy physical exercise and stress · Smoking cigarettes · Third-trimester pregnancy and labor · Chronic leukemia |
Known as neutropenia · Myelodysplastic syndrome · Severe infections like sepsis · Certain drugs like penicillin, ibuprofen, etc. · Autoimmune disorders · Chemotherapy · Cancer that spreads to bone marrow · Aplastic anemia |
|
Lymphocytes |
Known as lymphocytosis · Acute viral infections like hepatitis, chicken pox, herpes, etc. · Certain bacterial infections like whooping cough, tuberculosis, etc. · Lymphoma · Lymphocytic leukemia |
Known as lymphopenia or lymphocytopenia · Autoimmune disorders like systemic lupus erythematosus, rheumatoid arthritis, etc. · Infections like AIDS, tuberculosis, hepatitis, influenza, etc. · Bone marrow damage due to chemotherapy · Immune deficiency |
|
Monocytes |
Known as monocytosis · Chronic infections · Heart infections like bacterial endocarditis · Collagen vascular diseases like systemic lupus erythematosus, scleroderma, rheumatoid arthritis, vasculitis, etc. · Inflammatory bowel disease · Monocytic leukemia · Chronic and juvenile myelomonocytic leukemia |
Known as monocytopenia A single low count is medically insignificant. Low counts in subsequent tests may be indications of health conditions. Repeated low counts can indicate: · Hairy-cell leukemia · Bone marrow damage or failure |
|
Eosinophils |
Known as eosinophilia · Asthma · Allergies such as hay fever · Drug reactions · Inflammation of skin like eczema, dermatitis, etc. · Parasitic infections · Inflammatory diseases like celiac disease, inflammatory bowel disease, etc. · Certain cancers · Hypereosinophilic myeloid neoplasms |
Known as eosinopenia Eosinophil count is normally low and lower than normal counts may be difficult to determine. One or an occasional low number is usually not medically significant. |
|
Basophils |
Known as basophilia · Rare and severe allergic reactions like hives, food allergy · Inflammation due to rheumatoid arthritis, ulcerative colitis, etc. · Some leukemias like chronic myeloid leukemia |
Known as basopenia Basophil count is normally low and lower than normal counts may be difficult to determine. One or an occasional low number is usually not medically significant. |
Answers to Patient Concerns & Frequently Asked Questions (FAQs) about Differential Leukocyte Count
Frequently Asked Questions about Differential Leukocyte Count
Q. What is the purpose of the Differential Leukocyte Count test?
Q. What happens if the DLC count is high?
Q. What happens if the DLC count is low?
Q. Why is the Differential Leukocyte Count test more useful than the total leukocyte count test?
Q. Is there any risk associated with the Differential Leukocyte Count test?
References
- Blumenreich MS. The White Blood Cell and Differential Count. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd edition. Boston: Butterworths; 1990. Chapter 153. [Accessed 30 Jan. 2023]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK261/
- Blood Cell Count with Differential [Internet]. National Cancer Institute; 02 Feb. 2011 [Accessed 25 Jan. 2023]. Available from: https://www.cancer.gov/publications/dictionaries/cancer-terms/def/blood-cell-count-with-differential
- Types of White Blood Cells: What the Numbers May Mean [Internet]. Buffalo, USA: Roswell Park Comprehensive Cancer Center; 09 Jul. 2020 [Accessed 25 Jan. 2023]. Available from: https://www.roswellpark.org/cancertalk/202007/types-white-blood-cells-what-numbers-may-mean
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