Polycythemia vera (pol-e-sy-THEE-me-uh VEER-uh) is a type of blood cancer. It causes your bone marrow to make too many red blood cells. These excess cells thicken your blood, slowing its flow, which may cause serious problems, such as blood clots.
Polycythemia vera is rare. It usually develops slowly, and you might have it for years without knowing. Often the condition is found during a blood test done for another reason.
Without treatment, polycythemia vera can be life-threatening. But proper medical care can help ease signs, symptoms and complications of this disease.
Many people with polycythemia vera don't have noticeable signs or symptoms. Some people might develop vague symptoms such as headache, dizziness, fatigue and blurred vision.
More-specific symptoms of polycythemia vera include:
Itchiness, especially after a warm bath or shower
Numbness, tingling, burning, or weakness in your hands, feet, arms or legs
A feeling of fullness soon after eating and bloating or pain in your left upper abdomen due to an enlarged spleen
Unusual bleeding, such as a nosebleed or bleeding gums
Painful swelling of one joint, often the big toe
Shortness of breath and difficulty breathing when lying down
When to see a doctor
Make an appointment with your doctor if you have signs or symptoms of polycythemia vera.
Polycythemia vera occurs when a mutation in a gene causes a problem with blood cell production. Normally, your body regulates the number of each of the three types of blood cells you have — red blood cells, white blood cells and platelets. But in polycythemia vera, your bone marrow makes too many of some of these blood cells.
The cause of the gene mutation in polycythemia vera is unknown, but it's generally not inherited from your parents.
Polycythemia vera can occur at any age, but it's more common in adults between 50 and 75. Men are more likely to get polycythemia vera, but women tend to get the disease at younger ages.
Possible complications of polycythemia vera include:
Blood clots. Increased blood thickness and decreased blood flow, as well as abnormalities in your platelets, raise your risk of blood clots. Blood clots can cause a stroke, a heart attack, or a blockage in an artery in your lungs or a vein deep within a leg muscle or in the abdomen.
Enlarged spleen. Your spleen helps your body fight infection and filter unwanted material, such as old or damaged blood cells. The increased number of blood cells caused by polycythemia vera makes your spleen work harder than normal, which causes it to enlarge.
Problems due to high levels of red blood cells. Too many red blood cells can lead to a number of other complications, including open sores on the inside lining of your stomach, upper small intestine or esophagus (peptic ulcers) and inflammation in your joints (gout).
Other blood disorders. In rare cases, polycythemia vera can lead to other blood diseases, including a progressive disorder in which bone marrow is replaced with scar tissue, a condition in which stem cells don't mature or function properly, or cancer of the blood and bone marrow (acute leukemia).