The white blood cells (WBCs), also known as leukocytes, are essential to the immune system. The cell’s ability to fight against infections depends on the WBC count in the blood. In an adult person, the ideal WBC count should be between 4500 and 11000 per microlitre of blood. Someone with a high WBC count would have leukocytes of more than 11000 in a microlitre of blood. This condition is known as leukocytosis. It can be of the following types: Lymphocytic leukocytosis: Lymphocytes are a type of WBC that are a vital part of the immune system. These leukocytes ward off parasites, fungal growth, viruses, and bacteria. However, a high count of these cells is the most common cause of two known types of blood cancers: lymphocytic leukaemia and lymphoma.  Neutrophilic leukocytosis: Neutrophils are another type of leukocytes or WBCs. These also provide protection against fungal growth, bacteria, and parasites. Neutrophils also play a vital role in the injury healing process. However, the number of neutrophils can increase due to myeloid leukaemia, causing an increased number of immature neutrophils in the bloodstream.  Non-malignant leukocytosis: WBC disorders can be non-malignant as well as malignant. The non-malignant type of leukocytosis is mostly infections in the body. These can occur due to poor lifestyle choices like smoking, obesity and genetic conditions such as Down’s syndrome.  Malignant leukocytosis: Malignant leukocytosis is commonly referred to as blood cancer and causes sweating, rapid weight loss, and fever. Other symptoms include swollen liver, lymph nodes, and enlarged spleen. Similarly, a lower WBC count can cause neutropenia, which has the following symptoms: Recurring fever and infections Painful bladder infections Lung infections and coughing Difficulty breathing  Oral sores  Skin infections  Sinus infections and blocked nose Doctors often prescribe the TLC, DLC, and ESR tests as a part of a routine health checkup. Recurring fever or other symptoms can also be the reason doctors recommend these tests. Apollo 24|7 offers a complete package of TLC, DLC, and ESR tests comprising seven different tests at an affordable range. You can book the test online, and a phlebotomist will visit you to collect the blood sample. It is not a very painful or lengthy procedure, and only a small amount of blood is collected from your veins via the venipuncture method. The total leucocyte count (TLC) test helps determine the actual number of WBCs in the body. This is crucial to ensure that the WBC count is within the ideal range. Doctors can prescribe treatment accordingly if the result shows the count to be too low or too high. The differential leukocyte count (DLC) test offers a greater insight into the WBCs. This test helps measure the percentage of every single type of WBC in the blood. There are five types of WBCs: Three types of granulocytes Neutrophils  Eosinophils  Basophils Two types of Lymphocytes T-cells B-cells  Monocytes Erythrocytes are the red blood cells in the body. These consist of haemoglobin (Hb), which is responsible for carrying oxygen to the cells and transporting carbon dioxide to the lungs. The erythrocyte sedimentation rate (ESR) helps reveal any ongoing inflammatory activity within the body. Although it is not a diagnostic tool alone, along with the TLC and DLC rate, it helps monitor or diagnose the diseases. Apart from confirming blood cancer and infections, these tests can also help determine: Polymyalgia rheumatica  Rheumatoid arthritis  Giant cell arteritis