Complete Blood Count (CBC) Test, Values, and Interpretation Information on MedicineNet.com

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Complete Blood Count (CBC)

Medical Author: Siamak Nabili, MD, MPH
Medical Editor: William C. Shiel, Jr., MD, FACP, FACR

What Does a High White Platelet Count Mean?

Medical Author: Benjamin Wedro, MD, FAAEM
Medical Editor: Melissa Conrad Stöppler, MD

Viewer Question: What are some of the potential diagnoses when a person has a high platelet count? (Platelet count approximately 420?)

Dr. Stöppler's Response: Platelets are the smallest cell-like structures in the blood and are important for blood clotting and plugging damaged blood vessels. Platelet counts are usually done by laboratory machines that also count other blood elements such as the white and red cells. Normal platelet counts are in the range of 150,000 to 400,000 per microliter (or 150 - 400 x 109 per liter), but the normal range for the platelet count varies slightly among different laboratories.

What is the complete blood count test (CBC)?

The complete blood count (CBC) is one of the most commonly ordered blood tests. The complete blood count is the calculation of the cellular (formed elements) of blood. These calculations are generally determined by special machines that analyze the different components of blood in less than a minute.

A major portion of the complete blood count is the measure of the concentration of white blood cells, red blood cells, and platelets in the blood.

How is the complete blood count test (CBC) done?

The complete blood count (CBC) test is performed by obtaining a few milliliters (one to two teaspoons) of blood sample directly form the patient. It can be done in many settings including the doctor's office, laboratories, and hospitals. The skin is wiped clean with an alcohol pad, and then a needle is inserted through the area of cleansed skin into to patient's vein (one that can be visualized from the skin.) The blood is then pulled from the needle by a syringe or by a connection to a special vacuumed vial where it is collected. This sample is then taken to the laboratory for analysis.