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
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