Polycythemia vera is a rare slow-growing type of blood cancer in which the 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 the blood and cause complications, such as such as a risk of blood clots or bleeding.



Since it usually develops slowly, the patient may have it for years without noticing signs or symptoms. For many patients, Polycythemia vera may not even cause any signs or symptoms. However, some people may experience:

  • High blood pressure;
  • Headache and blurred vision;
  • Dizziness;
  • Weakness;
  • Excessive sweating;
  • Discomfort in the abdomen;
  • Painful swelling of one joint, often the big toe;
  • Breathing difficulty when patients lie down;
  • Numbness, tingling, burning or weakness in the hands, feet, arms or legs;
  • A feeling of fullness or bloating in the left upper abdomen due to an enlarged spleen;
  • Red skin, particularly in the face, hands and feet;
  • Bleeding problems – such as nosebleeds and bruising;
  • Gout, which can cause joint pain, stiffness and swelling.



Polycythemia vera occurs when a mutation in a bone marrow cell causes a problem with the blood cell production. Normally, the body carefully regulates the number of each of the three types of blood cells. However, in Polycythemia vera, this regulatory mechanism becomes damaged and the 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. Most people with Polycythemia vera have this kind of mutation. It's not clear what causes the mutations, but researchers believe that they occur after conception, so it's acquired, rather than inherited from a parent.


Risk Factors

The risk of Polycythemia vera increases with age. It is more common in adults older than 60, though the disease can occur at any age.



Without any or without a proper 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.

Possible complications of Polycythemia vera include:

  • Blood clots
  • Enlarged spleen
  • Skin problems
  • Problems due to high levels of red blood cells
  • Other blood disorders



Unfortunately, there's no way to prevent Polycythemia vera. However, the risk of secondary Polycythemia may be reduced by healthy lifestyle and by not spending long periods of time at high altitudes. Also, the symptoms and complications can be prevented or delayed with proper treatment.