What is polycythemia vera (PV)?
PV is a blood disorder in which the body makes too many red blood cells. These extra red cells make blood thicker than normal. The thickened blood flows slower and may clot within your body.
Red blood cells carry oxygen to organs and tissues throughout the body. If the blood moves too slowly or clots, the cells cannot deliver enough oxygen. This situation can cause serious complications including heart attack, stroke, and heart failure.
PV affects about 22 out of every 100,000 people. Doctors diagnose it most commonly in men over 60 years old.
Symptoms and Causes
What causes polycythemia vera (PV)?
Doctors classify PV into 2 types. The cause of the condition determines each type.
- Primary PV occurs when there is a genetic mutation (abnormality). Almost all people diagnosed with PV have a mutation in the JAK2 (Janus kinase) gene. In most cases, PV is not hereditary (passed down through families), but it is hereditary in a few cases. Mutations in the TET2 gene are also found commonly in PV cells.
- Secondary PV (acquired) occurs in people who experience low levels of oxygen in their blood for long periods of time. This extended lack of oxygen causes the body to make extra amounts of a hormone called erythropoietin (EPO). Too much EPO in the body can cause it to make too many red blood cells.
What are the symptoms of polycythemia vera (PV)?
People with PV experience a variety of symptoms. Some people have no symptoms at all. Symptoms include:
- Tiredness and weakness
- Difficulty breathing when lying down
- Enlarged (bigger than normal) spleen (organ that clears blood cells from the body)
- Blurry or double vision
- Itchy skin, especially following a warm bath
- Skin that is reddish or purplish in color
- Bleeding gums
- Weight loss
- Tinnitus (ringing in the ears)
- Sweating, especially at night
Diagnosis and Tests
How do doctors diagnose polycythemia vera (PV)?
To diagnose PV, your doctor will perform a test called a complete blood count (CBC) to see if your number of red blood cells is higher than normal.
Your doctor may also test your blood to look for amounts of a hormone called erythropoietin. Lower-than-normal levels of this hormone can be a sign of PV. Doctors use genetic tests to identify the mutation in the JAK2 gene.
Management and Treatment
What are the treatments for polycythemia vera (PV)?
Doctors treat PV with a technique called phlebotomy. This procedure removes blood from your body. Red blood cells contain large amounts of iron. By removing iron from the body, the production of red blood cells by the bone marrow slows down.
During phlebotomy, a health professional will insert a needle into a vein and drain blood through a tube into a container. People with a new PV diagnosis typically undergo phlebotomy once a week until their red blood cell level becomes closer to normal. After that, they may have phlebotomy every three months to keep levels normal.
Doctors also prescribe medicines to treat PV. The most common drug used to treat PV is hydroxyurea (Hydrea®, Droxia®). This medicine helps slow the production of red blood cells. Some people with PV take aspirin every day because it helps thin the blood.
Two other drugs used to treat PV are ruxolitininib (Jakafi®), which is used for patients who do not respond to or cannot take hydroxyurea. Pegylated interferon (Pegasis®), is used to treat hepatitis C. However, an off-label use for the interferon has been used to treat patients with PV.
What are the complications of polycythemia vera (PV)?
The most dangerous complication of PV is a blood clot. When a clot travels to the heart or brain, it can cause a heart attack or stroke. A clot can also travel to the lungs (pulmonary embolism). These events can be fatal.
A bone marrow disorder called myelofibrosis is another potential complication of PV. Myelofibrosis leads to scarring in the bone marrow and anemia (low red blood cell count). In rare cases, PV can develop into a blood cancer called acute myeloid leukemia (AML). AML can lead to anemia and infection, and spread beyond the blood to other areas in the body.
Can polycythemia vera (PV)? be prevented?
For most patients, there is no clear cause to the PV and it cannot be prevented.
Outlook / Prognosis
What is the outlook for people with polycythemia vera (PV)?
There is no cure for PV. People with the condition usually need treatment their entire lives.
Regular doctor visits and blood tests can help ensure the disease does not get worse. PV treatment helps you manage the disorder to ease symptoms and avoid complications for a healthier life.
When should I call the doctor if I have polycythemia vera (PV) or think I might?
Contact your doctor if you develop symptoms of PV. Early diagnosis and treatment can help keep PV from interfering with daily life.
Consulting with a doctor who specializes in genetic conditions may help you learn how to manage issues related to living with PV. Ask your doctor for a referral for a genetic specialist for additional counseling.