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 the 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 the 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 from 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 the 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 the 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 the 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.
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. A blood sample once collected will then be sent to the laboratory.
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 the needle prick.