Total Leucocyte Count

Interpreting Results

Overview of TLC

What is TLC?

Leukocytes or white blood cells (WBCs) form a part of the immune system of the body. There are five types of WBCs in blood. Total Leukocyte Count Test measures the total amount of all the leukocytes in blood.

Why is TLC done?

The Total Leukocyte Count Test is performed:

    ·         As a part of Complete Blood Count (CBC) Test in regular health checkups

    ·         To help diagnose infections and inflammation

    ·        To help diagnose conditions that decrease WBC count like bone marrow disorders

    ·         To monitor bone marrow function

    ·         To monitor chemotherapy treatment

What does TLC Measure?

Blood is made up of different types of cells suspended in a fluid called plasma. These include erythrocytes or red blood cells, leukocytes or white blood cells, and platelets. Blood cells are produced by the hematopoietic cells in bone marrow and are then released into circulation. RBCs carry oxygen to the tissues, platelets help in blood clotting at a site of injury, and leukocytes form a part of the immune system of the body. WBCs are of five primary types: neutrophils, basophils, eosinophils, monocytes, and lymphocytes. Lymphocytes are further of three types: B-Lymphocytes, T-Lymphocytes, and natural killer (NK) cells. Neutrophils, basophils, eosinophils are collectively called granulocytes since they contain granules in cytoplasm.

Depending on various factors like age, gender, health condition, environmental factors, etc., varying amounts of different types of WBCs circulate in the blood. The bone marrow increases the production of WBCs in response to an infection or inflammation anywhere in the body. These WBCs are called to the site by a series of chemical signals, where they work to treat the condition. During this time, the total leukocyte count remains high in blood. Once the infection or inflammation subsides, WBC production by bone marrow decreases and WBC count in circulation falls back to normal levels. A continuously elevated WBC count may thus be an indication of a chronic condition that is not resolving naturally and might need urgent attention.

Apart from an infection or inflammation, WBC count in blood can also be affected by other conditions like disorders of the immune system, autoimmune conditions, cancer, etc. WBC count may be higher or lower than normal in these cases.

WBC count test serves as an indication of a condition affecting the body. Further tests are performed to confirm a particular condition and direct treatment.

Preparation for TLC

  • No special preparation required

Sample Type for TLC

The sample type collected for Total Leucocyte Count is: Blood

Interpreting TLC results


Normal range (Approx.):

    ·         Newborns: 9,000 to 30,000/mm3

    ·         Children below 2 years age: 6,200 to 17,000/ mm3

    ·         Children over 2 years age and adults: 5,000 to 10,000/ mm3

    Note: Normal range of leukocyte count depends on a number of 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.

    Higher than the normal leukocyte count indicates an infection or inflammation being treated by the body.

    Lower than the normal leukocyte count indicates improper functioning of the immune system.

    Leucocyte Count Test is to be followed up with other tests to determine the exact cause of the abnormal results, if any.

Answers to Patient Concerns & Frequently Asked Questions (FAQs) about TLC

Frequently Asked Questions about Total Leucocyte Count

Q. How is this test performed?
This test is performed on a blood sample. A syringe with a fine needle is used to withdraw blood from a blood vessel in your arm. The healthcare provider will tie an elastic band around your arm to make the blood vessels swell with blood. This makes it easier to withdraw blood. You may be asked to tightly clench your fist. Once the veins are clearly visible, the area is cleaned with an antiseptic solution and then the needle is inserted into the blood vessel to collect the sample. You will feel a tiny pinprick during the procedure. Blood sample once collected will then be sent to the laboratory.
Q. Is there any risk associated with this test?
There is no risk associated with the test. However, since this test involves a needle prick to withdraw the blood sample, in very rare cases, a patient may experience increased bleeding, hematoma formation (blood collection under the skin), bruising or infection at the site of needle prick.
Q. What is Leukocytosis?
Leukocytosis is a condition where the leukocyte count is higher than the normal range. This may occur due to: · Infections · Inflammation or inflammatory conditions like rheumatoid arthritis, allergies · Cancers like leukemia, myeloproliferative neoplasms · Conditions causing necrosis (tissue death) like severe burns, trauma, surgery, etc. · Cigarette smoking · Surgical removal of spleen · Allergy · Very heavy physical exercise · Pregnancy · Certain drugs like corticosteroids, epinephrine, heparin, lithium, etc.
Q. What is Leukopenia?
Leukopenia is the condition where leukocyte count is lower than the normal range. This may occur due to: · Damage to the bone marrow due to toxins, radiotherapy, chemotherapy · Bone marrow diseases that reduce leukocyte production like myelodysplastic syndrome, deficiency of vitamin B12 or folate · Lymphoma · Cancer that has metastasized (spread) to the bone marrow · Autoimmune conditions affecting WBCs like systemic lupus erythematosus (SLE) · Malnutrition · Liver or spleen diseases · Large scale or severe infections like sepsis · Immune system diseases like AIDS · Certain drugs like antibiotics, anticonvulsants, captopril, chemotherapy drugs, etc.
Q. Is there any preparation required before the Leukocyte Count Test?
Inform the doctor about any medications you may be taking. No other preparations are required unless specified by your doctor.
Q. What other tests can be prescribed by your doctor in case the results of Leucocyte Count Test is not normal?
Other tests that may be prescribed upon appearance of an abnormal result in the Leucocyte Count Test include: · Differential White Blood Cell Count Test · Complete Blood Count (CBC) Test · Neutrophil Test: Neutrophils are the leukocytes that are present in the highest amount in circulation and confer protection against a wide range of infections. Neutrophil Test measures the amount of neutrophils present in the blood to determine neutropenia (low neutrophil count; indicates greater susceptibility to infections) · Blood Smear Test · Bacterial and Viral Cultures · Tests for inflammation (Erythrocyte Sedimentation Rate, C-Reactive Protein, etc.) · Tests for autoimmune diseases (antinuclear antibody) · Allergy tests · Imaging tests (CT Scan, MRI, etc.) · Biopsy
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