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Pronunciations erythropoietin fibrosis hematocrit hemoglobin myelofibrosis myeloproliferative phlebotomy polycythemia polycythemia vera thrombocythemia

Polycythemia vera (primary polycythemia) is a disorder of the blood-producing cells of the bone marrow that results in overproduction of red blood cells.

In polycythemia vera, the excess of red blood cells increases the volume of blood and makes it thicker, so that it flows less easily through small blood vessels.

Polycythemia vera is rare, occurring in about 5 of every 1 million people. The average age at which the disorder is diagnosed is 60, and it rarely occurs before age 20. More men than women develop polycythemia vera. The cause is not known.

Symptoms and Complications

Often, people with polycythemia vera have no symptoms for years. The earliest symptoms usually are weakness, fatigue, headache, light-headedness, shortness of breath, and night sweats. Vision may be distorted, and a person may have blind spots or may see flashes of light. Bleeding from the gums and more bleeding than would be expected from small cuts are common. The skin, especially the face, may look red. A person may itch all over, particularly after bathing or showering. Burning sensations in the hands and feet or, more rarely, bone pain may be felt.

In some people, the number of platelets (cell-like particles that help the body form blood clots) in the bloodstream increases. The liver and spleen may enlarge, as both organs begin to produce blood cells and as the spleen removes more red blood cells from the circulation. As the liver and spleen enlarge, a sense of fullness in the abdomen may develop. Pain can suddenly become intense should a blood clot develop in blood vessels of the liver or spleen.

The excess of red blood cells may be associated with other complications, including stomach ulcers, gout, and kidney stones. The increase in the thickness (viscosity) of the blood can cause heart attacks and strokes and can block blood flow to the arms and legs, lungs, and eyes. Rarely, polycythemia vera progresses to leukemia.

Diagnosis

Polycythemia vera may be discovered through routine blood tests performed for another reason, even before a person has any symptoms. Levels of hemoglobin (the protein that carries oxygen in red blood cells) and the hematocrit (the percentage of red blood cells in the total blood volume) are abnormally high. The number of platelets and white blood cells may also be increased.

Most doctors consider a high hematocrit result to be an indication of polycythemia. However, the diagnosis cannot be based solely on the hematocrit result. Therefore, to help make the diagnosis, a test that uses radioactively labeled red blood cells to determine the total number of red blood cells in the body (red blood cell mass) is sometimes performed.

Once polycythemia is discovered, the doctor must determine if it is polycythemia vera or polycythemia due to another cause (secondary polycythemia). The person's medical history may help differentiate the two, but sometimes the doctor must investigate further.

Blood levels of erythropoietin Some Trade Names
EPOGEN
PROCRIT
, a hormone that stimulates the bone marrow to produce red blood cells, also may be measured. Levels of erythropoietin Some Trade Names
EPOGEN
PROCRIT
are extremely low in polycythemia vera but are normal or high in secondary polycythemia. Rarely, cysts in the liver or kidneys and tumors in the kidneys or brain produce erythropoietin Some Trade Names
EPOGEN
PROCRIT
; people with these conditions have high levels of erythropoietin Some Trade Names
EPOGEN
PROCRIT
and may develop secondary polycythemia.

Removal of a sample of bone marrow for examination under a microscope (bone marrow biopsy (see Symptoms and Diagnosis of Blood Disorders: Bone Marrow Examination) can also be helpful to diagnose polycythemia vera.

What Are Secondary and Relative Polycythemia? Secondary and relative polycythemia differ from polycythemia vera (which literally translates as “true polycythemia”) in that their causes are known. Secondary polycythemia is caused by oxygen deprivation, which can result, for example, from smoking, severe lung disease, or heart disease. In secondary polycythemia, a high concentration of red blood cells results from an actual increase in the erythropoietin Some Trade Names EPOGEN PROCRIT level in the blood. People who spend long periods of time in circumstances low in oxygen, such as fighter pilots and those who live at high altitude, sometimes develop polycythemia but do not have polycythemia vera.(see Other Illnesses That Develop at High Altitudes) Secondary polycythemia may be treated with oxygen. Smokers are advised to quit and are offered specific treatment to assist quitting. Any underlying disease that is causing the oxygen deprivation and secondary polycythemia is treated as effectively as possible. Phlebotomy is used to lower the number of red blood cells. In relative polycythemia, a high concentration of red blood cells results from abnormally low levels of fluid (plasma). The low plasma level can occur as the result of burns, vomiting, diarrhea, drinking an inadequate amount of fluids, and the use of diuretics (drugs that speed elimination of salt and water by the kidneys). Relative polycythemia is treated by giving fluids by mouth or intravenously and by treating any underlying conditions that are contributing to the low plasma level.

Prognosis and Treatment

Without treatment, about half of the people who have polycythemia vera with symptoms die in less than 2 years. With treatment, they live an average of 15 to 20 years.

Treatment does not cure polycythemia vera, but it does control it and can decrease the likelihood of complications, such as the formation of blood clots. The aim of treatment is to decrease the number of red blood cells. Usually, blood is removed from the body in a procedure called phlebotomy, similar to the way blood is removed when donating blood. A pint of blood is removed every other day until the hematocrit reaches a normal level, which is then maintained by removing blood every few months, as needed.

Because phlebotomy may increase the number of platelets and does not reduce the size of an enlarged liver or spleen, people who undergo phlebotomy may need drugs to suppress production of red blood cells and platelets. Hydroxyurea Some Trade Names
HYDREA
, a chemotherapy drug, is frequently given, but when used for many years there is concern that it may increase the risk of transformation to leukemia. Alternative drugs for lowering the number of platelets, such as interferon-alpha and anagrelide Some Trade Names
AGRYLIN
, are sometimes used in younger people who may need treatment for long periods. Some people are given radioactive phosphorus intravenously, but doctors restrict this type of treatment to people older than 70 because of the potential for transformation to leukemia.

Other drugs can help control some of the symptoms. For example, antihistamines can help relieve itching, and aspirin Some Trade Names
ECOTRIN
ASPERGUM
can relieve burning sensations in the hands and feet as well as bone pain.

Last full review/revision February 2003