Neoplasm in which bone marrow makes too many red blood cells, and possibly white cells and platelets, causing thickening of blood.Encyclopedia Entry for Polycythemia Vera :Polycythemia vera. PV is a disorder of the bone marrow. It mainly causes too many red blood cells to be produced. The numbers of white blood cells and platelets may also be higher than normal. PV is a rare disorder that occurs more often in men than in women. It is not usually seen in people under age 40. The problem is often linked to a gene defect called JAK2V617F. The cause of this gene defect is unknown.With PV, there are too many red blood cells in the body. This results in very thick blood, which can't flow through small blood vessels normally, leading to symptoms such as: Trouble breathing when lying down Bluish skin Dizziness Feeling tired all the time Excess bleeding, such as bleeding into the skin Full feeling in the left upper abdomen (due to enlarged spleen) Headache Itchiness , especially after a warm bath Red skin coloring, especially of the face Shortness of breath Symptoms of blood clots in veins near the skin surface (phlebitis) Vision problems.The health care provider will perform a physical exam. You may also have the following tests: Bone marrow biopsy Complete blood count with differential Comprehensive metabolic panel Erythropoietin level Genetic test for the JAK2V617F mutation Oxygen saturation of the blood Red blood cell mass Vitamin B12 level PV may also affect the results of the following tests: ESR Lactate dehydrogenase (LDH) Leukocyte alkaline phosphatase Platelet aggregation test Serum uric acid.The goal of treatment is to reduce the thickness of the blood and prevent bleeding and clotting problems. A method called phlebotomy is used to decrease blood thickness. One unit of blood (about 1 pint, or 1/2 liter) is removed each week until the number of red blood cells drops. The treatment is continued as needed. Medicines that may be used include: Hydroxyurea to reduce the number of red blood cells made by the bone marrow. This drug may be used when the numbers of other blood cell types are also high. Interferon to lower blood counts. Anagrelide to lower platelet counts. Ruxolitinib (Jakafi) to reduce the number of red blood cells and reduce an enlarged spleen. This drug is prescribed when hydroxyurea and other treatments have failed. Taking aspirin to reduce the risk of blood clots may be an option for some people. But, aspirin increases the risk of stomach bleeding. Ultraviolet-B light therapy can reduce the severe itching some people experience.PV usually develops slowly. Most people do not have symptoms related to the disease at the time of diagnosis. The condition is often diagnosed before severe symptoms occur.Complications of PV may include: Acute myelogenous leukemia ( AML ) Bleeding from the stomach or other parts of the intestinal tract Gout (painful swelling of a joint) Heart failure Myelofibrosis (disorder of the bone marrow in which the marrow is replaced by fibrous scar tissue) Thrombosis (blood clotting, which can cause a stroke , heart attack , or other body damage).Call your provider if symptoms of PV develop.Primary polycythemia; Polycythemia rubra vera; Myeloproliferative disorder; Erythremia; Splenomegalic polycythemia; Vaquez's disease; Osler's disease; Polycythemia with chronic cyanosis; Erythrocytosis megalosplenica; Cryptogenic polycythemia.Kremyanskaya M, Najfeld V, Mascarenhas J, Hoffman R. The polycythemias.