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Polycythemia vera is a bone marrow disease that leads to an abnormal increase in the number of blood cells. The red blood cells are mostly affected.
Most of the health concerns associated with polycythemia vera are caused by the blood being thicker as a result of the increased red blood cells. It is more common in the elderly and may be symptomatic or asymptomatic. Common signs and symptoms include itching (pruritus), and severe burning pain in the hands or feet that is usually accompanied by a reddish or bluish coloration of the skin. Patients with polycythemia vera are more likely to have gouty arthritis. Treatment consists primarily of phlebotomy.
Symptoms and Complications
Many people have no symptoms when they are first diagnosed with polycythaemia vera. The disease is often discovered during a routine blood test or physical examination.
If symptoms do develop, they tend to do so over time. . They are mainly due to the increased thickness (hyperviscosity) and abnormally high numbers of blood cells in the circulating blood. Common symptoms include headaches, blurred vision, fatigue, weakness, dizziness, itchy skin and night sweats.
Enlargement of the spleen (splenomegaly) is also common and occurs in around 75 per cent of cases. Symptoms include feelings of discomfort, pain or fullness in the upper left-side of the abdomen. An enlarged spleen may also cause pressure on the stomach causing a feeling of fullness, indigestion and a loss of appetite. In some cases the liver may also be enlarged.This is called hepatomegaly.
Some people experience gout, which usually presents as a painful inflammation of the big toe or foot. This can result from a build up of uric acid, a byproduct of the increased production and breakdown of blood cells. Some individuals may develop erythromelalgia, a rare condition that primarily affects the feet and, less commonly, the hands. It is characterised by intense, burning pain of affected extremities, and increased skin temperature that may be episodic or almost continuous in nature.
In many cases, people with polycythaemia vera have a ruddy (red) complexion, and a reddening of the palms of the hand and soles of the feet, ear lobes, mucous membranes and the eyes. This is due to the high numbers of red cell in the circulation. A raised blood pressure (hypertension) is also common.
Causes of Polycythemia Vera
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.
Polycythemia Vera Diagnosis
In many cases, the diagnosis is incidental, often after a routine complete blood count which reveals in increase in the red blood cells, along with an increase in the white blood cells and/or platelets. In other cases, doctors may recognize signs of the disease on an examination, including a redness to the complexion, or an increase in the size of the spleen.
Common diagnostic tests include:
• Complete blood count, revealing in increase in the hemoglobin (along with the white blood cells and/or platelets
• JAK2 V617F mutation (positive in 95% of patients)
• Low erythropoietin level (a hormone involved in red blood cell production—it is low because blood cell production is being driven by another stimulus in JAK2 V617F)
• Bone marrow biopsy, revealing an excess in the proliferation of precursors to red blood platelets, red blood cells, and white blood cells
Affected Populations by Polycythemia Vera
Polycythemia vera affects slightly more men than women. The disorder is estimated to affect approximately 2 people per 100,000 in the general population. It occurs most often in individuals more than 60 years old, but can affect individuals of any age. It is extremely rare in individuals under 20.
Exams and Tests
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
This disease may also affect the results of the following tests:
- Lactate dehydrogenase (LDH)
- Leukocyte alkaline phosphatase
- Platelet aggregation test
- Serum uric acid
Polycythemia Vera 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.
Available Treatment for Polycythemia Vera
The goal of treatment is to reduce the thickness of the blood and prevent bleeding and clotting.
A method called phlebotomy is used to decrease blood thickness. One unit of blood (about 1 pint) is removed each week until the number of red blood cells drops. The treatment is continued as needed.
Other treatments may include:
- Chemotherapy (specifically hydroxyurea) to reduce the number of red blood cells made by the bone marrow. This option may used when the numbers of other blood cell types are also high.
- Interferon to lower blood counts.
- Anagrelide to lower platelet counts
Taking aspirin to reduce the risk of blood clots may be an option for some people. However, aspirin increase the risk of stomach bleeding.
Ultraviolet-B light therapy can reduce the severe itching some patients experience.