Myeloproliferative disorders are diseases in which the bone marrow produces too many of one of the three types of blood cells:
Red blood cells, which carry oxygen to all the tissues in the body
White blood cells, which fight infection
Platelets, which make blood clot
Polycythemia vera is a rare blood disorder in which there is an increase in all blood cells, particularly red blood cells. The increase in blood cells makes the blood more viscous (thick), leading to strokes or tissue and organ damage.
Polycythemia vera is one type of myeloproliferative disorder (MPD). Bone marrow contains stem cells that have the ability to mature into adult blood cells that enter the circulation, including red blood cells, white blood cells, and platelets. These stem cells are referred to as pluripotent hematopoeitic precursor cells, or PHPC, due to their versatility. Each PHPC can reproduce itself (clone), in addition to producing daughter cells, called blasts.
In MPD, one abnormal PHPC clone has an ability to overgrow and self-renew more effectively then normal PHPC clones. In polycythemia vera, there may be an increase in just the red blood cells, both the red and white blood cells, or in the red and white blood cells and platelets.
The abnormal PHPC clone is the result of mutations to genes in these cells. These mutations are not inherited, but happen during a person's lifetime. Why this happens to a given individual is unknown in most cases.
When there is an increase blood volume and viscosity (thickness), complications associated with this disease can occur. The following are the most common symptoms of polycythemia vera. However, each individual may experience symptoms differently. Symptoms may include:
- Fatigue and/or weakness
- Shortness of breath and difficulty breathing while lying down
- Visual disturbances, such as double vision, blurred vision, and blind spots
- Inability to concentrate
- Night sweats
- Flushed complexion
- Bleeding gums
- Excessive menstrual bleeding
- Hemoptysis (coughing up blood)
- Itchy skin (particularly after a hot bath)
- High blood pressure (hypertension)
Arterial or venous thrombosis, considered the most serious complications of polycythemia vera, can occur, resulting in a heart attack, stroke, or pulmonary embolism. Liver and spleen enlargement are other potential complications. The symptoms of polycythemia vera may resemble other blood disorders or medical problems. Always consult your doctor for a diagnosis.
In addition to a complete medical history and physical examination, diagnostic procedures for polycythemia may include blood tests to observe the increased number of red blood cells in the body, and distinguish it from other conditions which could cause the red blood cell count to increase (such as certain cardiac and respiratory diseases, erythremia, and certain tumors).
Specific treatment for polycythemia vera will be determined by your doctor based on:
- Your age, overall health, and medical history
- Extent of the disease
- Your tolerance for specific medications, procedures, or therapies
- Expectations for the course of the disease
- Your opinion or preference
Treatment may include:
- Phlebotomy. A procedure that involves removing blood from the body. Initially this must be done frequently, often every week, but once enough blood has been removed to deplete the body's iron stores, necessary to make blood quickly, it does not need to be done as often.
- Certain medications, including chemotherapy. Phlebotomy may not remove platelets effectively so medications are the treatment of choice if the platelets are dangerously high. The medicines help to keep your bone marrow from making too many blood cells, and keep your blood flow and blood thickness closer to normal.
- Radiation therapy. Radiation can help suppress overactive bone marrow cells. This therapy helps lower your red blood cell count and keeps your blood flow and blood thickness closer to normal.
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