polycythemia vera

Polycythemia vera, or PV, is a rare blood disease in which your body makes too many red blood cells (erythrocytes). These extra red blood cells make your blood thicker than normal. The thickened blood flows more slowly through your small blood vessels and can form clots. These clots can cause heart attack and stroke.


Blood cells are formed in your bone marrow – the soft tissue inside bones. In addition to red blood cells, your blood contains two other types of cells: white blood cells (leukocytes) to help fight infection and platelets to help your blood clot. If you have PV, your bone marrow produces too many red blood cells, but it also can make too many white blood cells and platelets.


Red blood cells also are called RBCs or erythrocytes. Normal red blood cells look like doughnuts without holes in the center and have an average lifespan of 120 days. Red blood cells contain hemoglobin, an iron-rich protein that gives blood its red color and carries oxygen to the body. Red blood cells also remove carbon dioxide, a waste product, from cells and carry it to the lungs to be exhaled.


General information

PV is a rare, chronic disease that can be fatal if not diagnosed and treated. The cause of PV is not known. It develops slowly and may not produce symptoms for many years. Sometimes, your symptoms can be vague and nonspecific. Many people find out they have PV from blood tests done for other reasons. It is more common in adult males 60 years or older. It is very rare in people younger than 20 years.


With PV, thicker than normal blood slows down the flow of blood to all parts of your body. Clots can form more easily, which can block blood flow through arteries or veins. The slower flow of blood means your organs don't receive enough oxygen. The shortage of oxygen can lead to angina, congestive heart failure, and gout. Slower blood flow also deprives your arms, legs, lungs, and eyes of the oxygen they need to perform normally. This can cause headaches, dizziness, itching, and problems with your vision, such as blurred or double vision.


PV may also cause you to develop stomach ulcers and kidney stones.


A small number of people with PV may develop myelofibrosis, a condition in which the bone marrow is replaced by fibrous (scar) tissue. The abnormal bone marrow cells may begin to grow out of control. This abnormal growth can lead to acute myelogenous leukemia (AML), a disease that worsens very quickly. In AML, too many immature white blood cells are found in the blood and bone marrow.



PV is a serious illness that can lead to death if it is not treated.


PV can be controlled with treatment, but no cure exists. If you think you or someone you know might have PV, it is important to talk to your doctor about it. Some people with PV need only minimal care. Others will need more intensive treatment. Treatment can control PV and lessen the risk of blood clots, heart attack, and stroke that can result from the disease.



Polycythemia vera (PV) is also known as primary polycythemia. It begins with a change to the DNA, a molecule present in every living cell, which forms genes – the hereditary material of the cell. This change is called a mutation. A mutation in the JAK 2 gene causes PV. The JAK 2 gene produces an important protein involved in blood production. Doctors and researchers do not know what causes the JAK 2 gene to change. The mutation of the JAK 2 gene occurs after conception. It is not passed from parent to child. The mutation of the JAK 2 gene cannot be reversed.


There is another kind of polycythemia not related to the JAK 2 gene. This is called secondary polycythemia. The cause of secondary polycythemia is known. It is caused by long-term exposure to low levels of oxygen. Long-term lack of oxygen can cause your body to produce more of the hormone erythropoietin (EPO). EPO increases the production of red blood cells above normal levels, leading to thickening of the blood as in PV. People who smoke, spend long hours at high altitudes (such as mountaineers and pilots), or have severe lung or heart disease may develop secondary polycythemia. In some cases, secondary polycythemia can be cured, depending on whether the underlying cause can be controlled or cured.


Who is at risk?

Polycythemia vera (PV) is a very rare blood disease. There are five new cases of PV per year for every 1 million people. It is more common in adults who are older than 60 years and is rarely found in people who are younger than 20 years. Men have a greater risk of developing PV than women.


Signs and symptoms


Major signs and symptoms

Polycythemia vera (PV) develops very slowly. You may not see signs and symptoms of PV for years after you have the condition. The signs and symptoms of PV are the result of the above normal thickness of your blood. This slows the flow of blood and the oxygen blood carries to all parts of your body. Without enough oxygen, the parts of your body can have problems functioning normally.


The most common signs and symptoms of PV include headache, dizziness, weakness, shortness of breath, difficulty breathing when you're lying down, feelings of pressure or fullness on the left side of the abdomen due to enlargement of the spleen, double or blurred vision, blind spots, itching all over (especially after a warm bath), reddened face, burning sensation in your skin (especially your hands and feet), bleeding from your gums, more than normal bleeding from small cuts, and unexplained weight loss. In rare cases, you may experience pain in your bones if you have PV.


Possible complications

If you have PV, the above normal thickness of your blood and slower blood flow can create serious health problems for you. The most serious complication of PV is that it may cause your blood to form clots. Blood clots can cause you to suffer a heart attack or stroke. They also can cause your liver and spleen to enlarge. Blood clots in the liver and spleen can cause sudden and intense pain. The high levels of red blood cells that cause PV can lead to stomach ulcers, gout, or kidney stones.



You may have polycythemia vera (PV) before signs or symptoms appear. Many times, doctors discover their patients have PV through routine blood tests performed for other reasons. If you have no clear symptoms for PV, but show higher than normal levels of hemoglobin and hematocrit in your blood test, your doctor may want to do more tests.


Doctors diagnose PV based on symptoms, physical exam, age, test results, and overall health, including other chronic diseases. The doctor will find out as much as possible about your medical history. Your doctor will look for signs of polycythemia during your physical exam, including enlargement of the spleen, reddened skin on the face, and bleeding from the gums. If your doctor confirms that you have polycythemia, the next step is to determine if you have PV or secondary polycythemia.


Often, your medical history and physical exam can confirm which type of polycythemia you have. If not, your doctor may order tests that check the level of erythropoietin (EPO) in your blood. Patients with PV have extremely low levels of EPO. Patients with normal to high levels of EPO in their blood more than likely suffer from secondary polycythemia.


Specialists involved

If your primary care doctor suspects you have PV, you may be referred to a hematologist (a doctor who is an expert in treating blood conditions).


Diagnostic tests and procedures

The doctor treating you may order a number of different blood tests to diagnose PV. These tests include a complete blood count (CBC), conducted along with other tests if necessary.


  • The CBC counts the numbers of all three types of blood cells – red blood cells that carry oxygen, white blood cells that fight infection, and platelets that help clot the blood. If your CBC shows higher than normal counts of these cells, especially the red blood cells, you may have PV.

  • The CBC also measures hemoglobin, the iron-rich protein in red blood cells that carries oxygen through the body. A higher than normal hemoglobin level may be a sign that you have PV.

  • The hematocrit part of the CBC measures the percentage of blood that consists of red blood cells. A higher than normal hematocrit level may be a sign that you have PV.

    Your doctor may order additional blood tests to confirm a diagnosis of PV:


  • A blood smear. A sample of your blood is viewed under a microscope to collect information about the number and shape of blood cells. Your doctor will examine the smear for the high concentration of red blood cells seen in PV and for abnormal types of blood cells that are seen in myelofibrosis and other conditions related to PV.

  • Arterial blood gas test. A sample of your blood is taken from an artery to measure the amount of oxygen, carbon dioxide, and pH (acidity) in the blood. If your test results show a lower than normal level of oxygen in your blood, it may be a sign you have PV.

  • EPO level. Your blood is tested to measure the level of EPO, a hormone that stimulates bone marrow to produce new blood cells. If you have PV, this test result will show lower than normal levels of EPO in your blood.

  • Red blood cell mass. This test usually takes place in a hospital in the nuclear medicine department. The health professional performing the test takes a sample of your blood. A very weak radioactive dye is mixed with your blood sample. The weak dye attaches itself to the red blood cells and plasma in your sample. The tagged cells in your sample are injected back into your bloodstream and spread quickly throughout your body. By taking another sample of your blood, or using special cameras sensitive to the dye, technicians can figure out the total number of red blood cells in your body. Higher than normal red blood cell counts may be a sign you have PV.

    In some cases, your doctor may want to do a bone marrow biopsy or aspiration. A bone marrow biopsy is a minor surgical procedure your doctor performs to remove a small amount of bone marrow tissue with a needle from your body. In a bone marrow aspiration, your doctor removes a small amount of bone marrow fluid through a needle. Bone marrow biopsy or aspiration tests whether your bone marrow is healthy and producing a normal amount of blood cells. If the test shows that your bone marrow is producing higher than normal amounts of blood cells, it may be a sign you have PV.



    Your doctor may treat your polycythemia vera (PV) with a number of methods, either separate or in combination. Your treatment options may include phlebotomy, medicines, or biological therapy.


    Goals of treatment

    PV cannot be cured. The goals of treating PV are to control your symptoms and reduce the risk of complications, especially stroke or heart attack, caused by thickened blood and blood clots. This is done by reducing the number of red blood cells and hemoglobin in your blood toward normal levels. Reducing the number of red blood cells and hemoglobin brings the thickness of your blood closer to normal levels. Blood with normal thickness flows more easily through the arteries. This reduces the chances that blood clots will form that could cause you to have a stroke or heart attack. Blood with normal thickness delivers oxygen more efficiently to all parts of your body. This can help reduce some of the signs and symptoms PV causes, such as headaches, vision problems, and itching.


    Studies show that treatment of PV greatly improves your chances of living longer.


    Specific types of treatment



    In phlebotomy, your doctor or technician removes some of your blood from a vein (similar to what is done when you donate blood). A needle is inserted into your vein, and your blood flows through an airtight tube into a sterile container or bag. This reduces the number of red blood cells in your system and begins the process of bringing your blood thickness closer to normal levels. Typically, a pint (1 unit) of blood is removed each week until your hematocrit (the measure of what percentage of a tube of blood consists of red blood cells) approaches a normal level. Then, you may continue to have phlebotomy performed every few months as needed.



    Your doctor may prescribe medicines to keep your bone marrow from making too many red blood cells. You may take hydroxyurea, a chemotherapy medicine, to reduce the numbers of red blood cells and platelets in your blood. By limiting or reducing the number of red blood cells in your blood, this medicine helps bring your blood thickness and blood flow closer to normal levels.


    Your doctor may advise you to take aspirin to relieve bone pain and the burning sensation in hands or feet that you may experience as a result of PV. Aspirin also reduces the chance of blood clots.


    Biological therapy (Immunotherapy)

    This form of treatment uses substances made naturally in the body to stimulate your immune response against overproduction of red blood cells. Your doctor may prescribe substances that your body normally produces, like interferon-alpha, if you have PV. These substances reduce the overproduction of blood cells by the bone marrow. This helps keep your blood thickness and blood flow closer to normal levels, reduces the chances of blood clots, and may reduce some of the signs and symptoms of PV.


    Other types of treatment

    If you have itching as a result of PV, your doctor may prescribe a number of prescription medicines to ease the discomfort you feel. These include cholestyramine, cyproheptadine, cimetidine, or psoralen. Your doctor also may prescribe ultraviolet light treatment and antihistamines to help relieve your itching.


    Your doctor may prescribe allopurinol if the level of uric acid in your blood is higher than normal.


    Your doctor may decide to treat you with radioactive phosphorus (P32) to suppress overactive bone marrow cells. This helps reduce the number of red blood cells in your blood, and keeps your blood's thickness and flow closer to normal levels.



    Polycythemia vera (PV) cannot be prevented. But with treatment, symptoms and complications can be prevented or delayed.


    Secondary polycythemia may be prevented in some cases by not doing things that deprive your body of normal levels of oxygen for a long time. Some things, like mountain climbing, living at high altitudes, or smoking, can be avoided or stopped.


    People with serious lung or heart disease may develop secondary polycythemia. In such cases, your doctor will treat the disease that deprives your body of oxygen as effectively as possible. Living a healthy lifestyle that reduces the chances of developing heart and lung disease will help you prevent secondary polycythemia as well.


    Living with polycythemia vera


    Preventing complications

    You may have polycythemia vera (PV) long before you see signs or symptoms of the disease. If you have PV, the sooner it is diagnosed, the sooner your doctor can begin treating you.


    Activities such as walking can help improve your blood circulation if you have PV. Moderate exercise that safely increases your heart rate improves the flow of blood to the parts of your body. Improving blood flow reduces the chances that you might develop blood clots. Leg and ankle stretching exercises also can help improve your blood circulation.


    If you have PV, you may experience itchiness all over as a symptom of the disease. It is important not to damage your skin from scratching. If bathing or showering causes you to have severe itching, try using cooler water and gentler soap. Dry your skin carefully and gently after baths and use moisturizing lotion on the skin.


    Due to poor blood flow in the hands and feet that results from PV, you may be more prone to injury from exposure to cold, heat, and pressure. If you have PV, it is important for you to avoid prolonged exposure to extremes in temperature or pressure.


  • In cold weather, you should wear warm clothing. Take particular care with your hands and feet. Warm gloves, socks, and shoes are very important protection for you.

  • Avoid extreme heat. Protect yourself from the sun. Drink plenty of liquids. Avoid hot tubs, heated whirlpools, or highly heated baths of any type. Be very careful of tanning booths, sun lamps, or heat lamps.

  • In playing sports or carrying out daily activities, guard against trauma or situations where your body is put under pressure. If you are injured, seek treatment as quickly as possible. Tell the person treating you that you have PV.

  • Check your feet regularly and report any sores to the doctor.

    Ongoing health care needs

    If you have PV, you will require regular medical care and monitoring of your condition for the rest of your life. It is important to see your doctor for any prescribed treatments for your PV. Your doctor will want to monitor your condition closely. This is important so that your doctor can detect any changes in your condition and treat them early, if necessary. Your doctor may need to perform periodic blood tests to determine the course of the disease. If your doctor prescribes medicine, you will need to take it as prescribed.


    Support groups

    The Myeloproliferative Disorders Foundation is a foundation that provides support for and information on PV.