Polycythemia vera (PV) is a rare blood disease in which your body makes too many red blood cells.
The extra red blood cells make your blood thicker than normal. As a result, blood clots can form more easily and block blood flow through your arteries and veins. This can lead to heart attack and stroke.
Thicker blood also flows more slowly to all parts of your body, preventing your organs from getting enough oxygen. This can cause other serious complications, such as as angina (chest pain) and heart failure.
PV also is known as primary polycythemia. A mutation, or change, in the JAK2 gene is the major cause of PV. This gene makes an important protein that helps the body produce blood cells. What causes the change in the JAK2 gene isn't known.
Another type of polycythemia, called secondary polycythemia, isn't related to the JAK2 gene. Long-term exposure to low oxygen levels causes secondary polycythemia.
PV is a very rare blood disease. It's more common in adults older than 60, and it's slightly more common in men.

The most common signs and symptoms of PV are headache, dizziness, weakness, shortness of breath, feelings of pressure or fullness on the left side of the abdomen (due to an enlarged spleen), double or blurred vision and blind spots, itching, reddened face, a burning feeling on the skin (especially the hands and feet), bleeding from the gums, heavy bleeding from small cuts, unexplained weight loss, and fatigue (tiredness).
PV may not cause signs or symptoms for years. Thus, the disease often is found during routine blood tests done for other reasons. PV is diagnosed based on your signs and symptoms, age and overall health, medical history, a physical exam, and test results.
PV can't be cured. However, treatments can help control the disease and its complications. PV is treated with procedures, medicines, and other methods.

The goals of treating PV are to control your symptoms and reduce the risk of complications due to thickened blood and blood clots.
Primary polycythemia can't be prevented. However, with proper treatment, you can prevent or delay symptoms and complications. Avoiding things that deprive your body of oxygen for long periods may prevent some cases of secondary polycythemia.

If you have PV, you will need lifelong medical care for the disease. Talk to your doctor about how often to schedule followup visits. Routine care will allow your doctor to detect any changes with your PV and treat them early, if needed. Follow your treatment plan and take all of your medicines as your doctor prescribes.

Points to remember about Polycythemia Vera.