What Does High Platelet Count Mean?

  • Medical Author:
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Ask the experts

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

Doctor'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.

An elevated platelet count is known as thrombocytosis. The laboratory where the test was performed will be able to tell whether a platelet count of 420,000 represents an elevated value for this laboratory. An elevated platelet count can be observed in people without significant medical problems. Mild to moderately elevated platelet counts are commonly seen when chronic inflammation is present. In other cases a high platelet count can signal a more serious blood problem known as a myeloproliferative disorder (abnormal growth of blood cell elements within the bone marrow). Your doctor may need to perform additional tests to determine the cause of an abnormally high platelet count.

Medically reviewed by John A. Daller, MD; American Board of Surgery with subspecialty certification in surgical critical care

REFERENCE:

"Approach to the patient with thrombocytosis"
UpToDate.com

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Last Editorial Review: 6/19/2017

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