What Is a Complete Blood Count Test?

A complete blood count test is a blood test that doctors perform to assess the overall health of a patient and diagnose various disorders, states Mayo Clinic. Such disorders include anemia, leukemia and infections.

A doctor can do a complete blood count test as a routine screening, as a follow-up test to monitor particular treatments or to asses the patient based on symptoms, according to MedicineNet. For instance, whereas a low red blood cell count indicates anemia, a high white blood cell count implies a body infection or a bone marrow infection.

Performing a complete blood count test involves testing a sample of blood taken directly from a patient, explains MedicineNet. To obtain a blood sample, a doctor wipes clean the patient's skin with an alcohol pad, inserts a needle into a visible vein through the cleaned skin and then pulls the blood into the syringe. The doctor then takes the sample to a laboratory for analysis.

A complete blood count test involves values such as white blood cell count, white blood cell differential count and red cell count, notes MedicineNet. Other values include, hemoglobin, mean corpuscular volume, mean corpuscular hemoglobin, hematocrit, red cell distribution, mean corpuscular hemoglobin concentration width and platelet count.