Ask The Expert
August 31, 2012
Platelets are a type of blood cell that play an important role in blood clotting. Platelets are made in the bone marrow. The bone marrow produces all types of blood cells.
A normal platelet count is between 150,000 and 450,000 platelets per microliter of blood. The bone marrow closely regulates the number of platelets that are produced and released into the blood stream. Both too low and too high levels of platelets can indicate a problem. Doctors use the term thrombocytosis to describe an increased platelet count.
Thrombocytosis has two general causes:
Conditions that can stimulate an otherwise normal bone marrow to produce too many platelets include:
If you have an elevated platelet count, your doctor will usually begin by looking for a specific cause. He or she may order more blood tests. You may also be referred to a hematologist. This is a specialist in disorders of the blood.
If no cause is found, you may need a bone marrow biopsy. Samples from the bone marrow are examined under the microscope. In addition, special testing can be performed that provides information to guide treatment.
If all of these tests are normal and no specific cause can be found for your high platelet count, you may be diagnosed with essential thrombocytosis. (As a medical term, essential means no other cause has been identified.) This is an uncommon condition that develops for unclear reasons.