Definition
Polycythemia is a condition that occurs when the bone marrow produces an abnormal and excessive amount of red blood cells and platelets in the blood. The abnormal increase of red blood cells in the blood can cause the blood to thicken and clot.
There are several forms of polycythemia—primary polycythemia, secondary polycythemia, and stress polycythemia—and each form has its own set of causes and risk factors.
Primary polycythemia is a serious and chronic condition that requires immediate care from your doctor. No cures exist for this condition, but there are treatment options. It is extremely important that you seek medical attention to establish a treatment plan.
Location of Active Bone Marrow in an Adult

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