Total Leucocyte Count, often abbreviated as TLC, is a medical test that measures the total number of white blood cells (leukocytes) in a person’s blood sample. White blood cells play a crucial role in the immune system, defending the body against infections and foreign invaders. Monitoring TLC is essential in diagnosing various medical conditions, including infections, autoimmune disorders, and certain cancers. A normal TLC range is typically between 4,000 and 11,000 white blood cells per microliter of blood, but this can vary depending on age, gender, and other factors. Abnormal TLC levels may indicate an underlying health issue and are an important diagnostic tool for healthcare professionals.