Testing a patient's leukocyte count involves blood testing. To do this, a healthcare professional will use a needle and insert it into the patient's vein. They will extract the amount of blood ordered by the patient's doctor. This will then be sent off to a laboratory to be analyzed.
The most common test is a standard blood count, also referred to as a total leukocyte count. It measures how many white blood cells a patient has per microliter of blood. This allows doctors to test a specific type of leukocyte to see if it is lower, or higher, that it should be.
Another test, called a differential count, will measure how many neutrophils, monocytes, basophils, lymphocytes, and eosinophils a patient has per microliter of blood. When healthy, the blood is made up of 60 percent neutrophils, 5 percent monocytes, 1 percent basophils, 30 percent lymphocytes, and 4 percent eosinophils.