Definition and Overview
Polycythemia vera is a rare type of blood cancer that occurs when the bone marrow produces an excessive amount of red blood cells and sometimes, platelets and white blood cells too. It is a kind of myeloproliferative neoplasm, which indicates an abnormality in the bone marrow.
The blood cells come in different types: platelets, red blood cells, and white blood cells, which all have a specific task. Red blood cells are responsible for delivering oxygen to other cells in the body while white blood cells are considered the army since they protect the body from threats such as viruses and bacteria. Platelets, on the other hand, helps prevent bleeding. These blood cells are produced in the bone marrow.
The body certainly needs a regular supply of these blood cells. Otherwise, the brain will starve if there’s not enough oxygen or the immunity will be compromised if the white blood count is low. However, excessive production of these cells can also lead to serious complications.
One, they can increase the viscosity of the blood. It’s important that the blood isn’t “sticky” enough so it can flow properly through the blood vessels such as the arteries and veins. If it has become too thick, it may cause thrombosis or clotting, both of which may cut the body’s much-needed blood supply. These can result in heart attack, stroke, high blood pressure, and other cardiovascular diseases.
As the bone marrow becomes abnormal, it may start producing blast cells or immature cells, which may drastically increase the risk of leukemia.
Polycythemia vera affects only a very small percentage of the population. Further, it can happen without any symptoms during the early stages. In fact, a good number of patients may never know it until they have gone through a routine exam.
Polycythemia vera is a slow-progressing disease, and depending on the treatment, its progress may be delayed for a very long time. When left alone, however, it can become life threatening.
Causes of Condition
Polycythemia vera has a genetic component, specifically JAK2V617F, which is actually a genetic defect. Interestingly, though, this gene mutation is seen right after the fetus is conceived. There are also other types of genes that are associated with the disease. However, scientists have no way of knowing why they behave that way. On the other hand, there is a small number of patients who develop the disease for no clear reason. Several studies are still being conducted to find out the real cause.
However, there are risk factors. The blood cancer is more likely to occur among those who are at least 60 years old. It’s rare to find patients who are under 40. Although it’s sometimes found among people with either Asian or European descent, it’s more common among Europeans who also have Jewish blood.
People who have been diagnosed with gout or acute myeloid leukemia may also need to have themselves tested for the disorder as about 3% of those with myeloid leukemia also have polycythemia vera.
- Difficulty in breathing especially when resting or lying down
- Consistent high levels of blood cells
- Feeling of fullness
- Inability to complete a full meal
- Weight loss
- Blurry vision
- Blood clot
- Thrombosis including deep vein thrombosis
- Jaundice (once the disease affects the liver)
- Frequent infections
- Red face
- Red spots on the skin
- Night sweats
- Swollen toe or foot (symptom of gout)
- Burning sensation of the extremities (erythromelalgia – this is a rare symptom)
A patient may also develop some discomfort in the upper abdomen. There’s a good chance this is caused by an enlarged spleen or splenomegaly. A spleen is often not immediately felt by touch. The best way to see it is through an imaging or ultrasound test. In its ideal size, it should be as big as the patient’s fist. The spleen, like the bone marrow, produces red and white blood cells. If the enlarged spleen is not immediately treated, it can rupture and cause abdominal bleeding. At least 65% of polycythemia vera patients have an enlarged spleen.
Who to See and Treatments Available
Since polycythemia vera is often diagnosed among adults, the best doctor to diagnose and treat it is an internist. The internist is the doctor for adults and has been trained to handle simple and complex diseases, including the rare ones. On the other hand, since this concerns the blood, a hematologist, an internist specializing in blood disorders, can also help. If it has progressed to or has caused leukemia, the patient may then be referred to an oncologist, who will help manage the cancer.
Different types of tests can be conducted to assess and diagnose the disease. These include a Complete Blood Count (CBC), which tells how much red and white blood cells, as well as platelets, are produced by the body. A mutation test to detect the presence of the gene defect can also be carried out, along with a bone marrow biopsy.
There’s no cure yet for the disease, and it may progress even if treatment is already provided. But a better quality of life may be achieved if the disease is managed promptly and properly.
Young patients or those who have a mild case of the disorder can benefit from a procedure called Phlebotomy (also called venesection) or the process of drawing blood from the veins to decrease the volume of blood cells in the body. As much as 500 ml can be obtained from the body in a procedure similar to that of donating blood. Depending on the levels of the hematocrit, the process may be repeated successively. For maintenance, the patient may undergo the procedure at least once a month.
When phlebotomy doesn’t work or the disease has become worse, the following treatments are considered:
- Drugs like hydroxyurea or chemotherapy that suppress the functions of the bone marrow or control the production of blood cells
- Aspirin (low-dose) to decrease the risk of a blood clot
- Antihistamines or UV light to minimize skin itching
- Interferon to regulate blood cell production
Surgery to treat an enlarged spleen or an affected liver
Kremyanskaya M, Najfeld V, Mascarenhas J et al. The polycythemias. In: Hoffman R, Benz EJ Jr, Silberstein LE, Heslop HE, Weitz JI, eds. Hematology: Basic Principles and Practice. 6th ed. Philadelphia, PA: Saunders Elsevier; 2012:chap 67.
Tefferi A. Polycythemias. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Saunders Elsevier; 2011:chap 169. http://www.leukaemia.org.au/blood-cancers/myeloproliferative-neoplasms-mpn/polycythaemia-vera