Polycythemia vera
DEFINITION
Polycythemia vera (pol-e-sigh-THEE-me-uh VEER-uh) is a slow-growing type of blood cancer in which your bone marrow makes too many red blood cells. Polycythemia vera may also result in production of too many of the other types of blood cells — white blood cells and platelets. These excess cells thicken your blood and cause complications, such as such as a risk of blood clots or bleeding.
Polycythemia vera isn’t common. It usually develops slowly, and you may have it for years without noticing signs or symptoms. Often, polycythemia vera is found during a blood test done for some other reason.
Without treatment, polycythemia vera can be life-threatening. However, with proper medical care, many people experience few problems related to this disease. Over time, there’s a risk of progressing to more-serious blood cancers, such as myelofibrosis or acute leukemia.
CAUSES
Polycythemia vera occurs when a mutation in a bone marrow cell causes a problem with blood cell production. Normally, your body carefully regulates the number of each of the three types of blood cells you have. But in polycythemia vera, the mechanism your body uses to control the production of blood cells becomes damaged, and your bone marrow makes too many of some blood cells.
The mutation that causes polycythemia vera is thought to affect a protein switch that tells the cells to grow. Specifically, it’s a mutation in the protein JAK2 (the JAK2 V617F mutation). Most people with polycythemia vera have this mutation. There are other mutations found in people with polycythemia vera, but it’s not yet known what role these mutations play in the development of the disease or what the implications of these mutations might mean for treating the disease.
It’s not clear what causes the mutations seen in polycythemia vera. Researchers believe the mutation occurs after conception — meaning that your mother and father don’t have it — so it’s acquired, rather than inherited from a parent.
SYMPTOMS
For many people, polycythemia vera may not cause any signs or symptoms. However, some people may experience:
- Itchiness, especially following a warm bath or shower
- Headache
- Dizziness
- Weakness
- Excessive sweating
- Painful swelling of one joint, often the big toe
- Shortness of breath
- Breathing difficulty when you lie down
- Numbness, tingling, burning or weakness in your hands, feet, arms or legs
- A feeling of fullness or bloating in your left upper abdomen due to an enlarged spleen
When to see a doctor
Make an appointment with your doctor for an evaluation if you have any of the signs or symptoms of polycythemia vera.
Because polycythemia vera causes your blood to thicken and slows blood flow, it increases your risk of developing blood clots. If a blood clot occurs in your head, it can cause a stroke. Seek emergency medical care if you have any of the following signs or symptoms of a stroke:
- Sudden numbness, weakness, or paralysis of your face, arm or leg — usually on one side of your body
- Sudden difficulty speaking or understanding speech (aphasia)
- Sudden blurred, double or decreased vision
- Sudden dizziness, loss of balance or loss of coordination
- A sudden, severe headache or an unusual headache, which may or may not be accompanied by a stiff neck, facial pain, pain between your eyes, vomiting or altered consciousness
- Confusion, or problems with memory, spatial orientation or perception
