ConditionBlood & immune system
Polycythemia Vera (PV)
Polycythemia vera (PV) is a rare, slow-growing blood cancer in which the bone marrow makes too many red blood cells, and often too many white cells and platelets. The thickened blood raises the risk of clots, strokes and heart attacks. Common symptoms are headaches, dizziness, a red face, itching after a warm shower and an enlarged spleen. Almost everyone with PV has a JAK2 gene mutation. Treatment with regular blood removal (phlebotomy), low-dose aspirin and sometimes medicines keeps it controlled for many years.
Also called: PV, primary polycythemia, polycythemia rubra vera, erythremia
At a glance
- What it is
- A myeloproliferative neoplasm with overproduction of red blood cells.
- Who
- Usually diagnosed around age 60; slightly more common in men.
- Cause
- An acquired JAK2 mutation in about 95 to 98 percent of cases.
- Symptoms
- Headache, dizziness, red face, itching after bathing, burning hands and feet, enlarged spleen, clots.
- Treatment
- Phlebotomy to keep hematocrit below 45 percent, low-dose aspirin, hydroxyurea, interferon or ruxolitinib if high risk.
When to get help
Call 911 or go to the ER
- Sudden weakness, numbness, facial droop, speech difficulty or vision loss: call 911 or your local emergency number (possible stroke)
- Chest pain, sudden breathlessness, or a swollen painful leg with breathlessness
- Severe abdominal pain with a swelling belly or jaundice (possible clot in liver or abdominal veins)
- Vomiting blood or black stools
See a doctor within a day or two
- A swollen, painful, warm leg (possible deep vein thrombosis)
- Burning, red, painful hands or feet, or new numbness or visual disturbances
- Left upper abdominal pain or early fullness from an enlarged spleen
Book a routine appointment
- A high hemoglobin or hematocrit on a routine blood test
- Itching after warm baths or showers, headaches and a ruddy complexion
- Night sweats, weight loss or fatigue in someone with PV
What polycythemia vera is
PV is one of the myeloproliferative neoplasms (MPNs), alongside essential thrombocythemia and myelofibrosis. A mutation in the JAK2 gene in a blood stem cell switches on cell growth signals permanently, so the marrow overproduces red cells regardless of the body's need. The extra cells make the blood thicker and slower-flowing, raising clot risk.
It is not usually inherited, though MPNs are somewhat more common in relatives.
Primary vs secondary polycythemia
| Polycythemia vera (primary) | Secondary polycythemia | |
|---|---|---|
| Cause | JAK2 mutation in marrow | Low oxygen or excess EPO: smoking, sleep apnea, lung or heart disease, high altitude, testosterone use, kidney tumors |
| EPO level | Low or low-normal | Normal or high |
| White cells and platelets | Often raised | Usually normal |
| Spleen | Often enlarged | Normal |
Symptoms
Many people are diagnosed after a routine blood test. Symptoms include:
- headaches, dizziness and ringing in the ears
- fatigue and weakness
- a red, ruddy face and red palms
- itching after a warm bath or shower (aquagenic pruritus), a classic clue
- burning pain, redness and warmth in the hands or feet (erythromelalgia)
- visual disturbances
- night sweats and weight loss
- fullness or pain in the upper left abdomen from an enlarged spleen
- gout from high cell turnover
- bleeding, such as nosebleeds or bruising, in some people
Clots
The most serious risk: stroke, heart attack, deep vein thrombosis, pulmonary embolism, and clots in abdominal veins (Budd-Chiari syndrome), which can be the first sign of PV in younger people.
Diagnosis
World Health Organization criteria include:
- high hemoglobin or hematocrit: hemoglobin over 16.5 g/dL in men or 16.0 g/dL in women, or hematocrit over 49 percent in men or 48 percent in women
- bone marrow biopsy showing increased production of all cell lines
- JAK2 V617F or exon 12 mutation
- low serum erythropoietin (EPO)
Other tests: complete blood count, iron studies (iron deficiency is common because of high red cell production or phlebotomy), and tests to exclude secondary causes.
Treatment
The main goals are to prevent clots and control symptoms.
For everyone
- phlebotomy: removing blood (like donating blood) to keep hematocrit below 45 percent; at first often every few days to weeks, then as needed
- low-dose aspirin to reduce clot risk, unless contraindicated
- managing cardiovascular risk: stop smoking, control blood pressure, cholesterol and diabetes
For high-risk patients
High risk means age over 60 or a previous clot. Treatment adds cytoreductive therapy:
- hydroxyurea: first-line for most
- interferon alfa (including ropeginterferon alfa-2b): often used in younger people and in pregnancy; can reduce JAK2 burden
- ruxolitinib: a JAK inhibitor for people who do not respond to or tolerate hydroxyurea, and for severe itching or enlarged spleen
Symptom control
- itching: antihistamines, SSRIs, phototherapy, ruxolitinib or interferon
- erythromelalgia responds to aspirin
Outlook
With treatment, many people with PV live for decades, and median survival is now commonly estimated at around 15 to 20 years or more after diagnosis, longer in younger patients. Over 10 to 20 years, some progress to myelofibrosis (post-PV myelofibrosis), and a small number to acute myeloid leukemia.
Frequently asked questions
What are the symptoms of polycythemia vera?
Common symptoms include headaches, dizziness, a red face, fatigue, itching after warm showers, burning hands or feet, night sweats and fullness in the upper left abdomen from an enlarged spleen. Some people are diagnosed only after a clot or a routine blood test.
What causes polycythemia vera?
It is caused by an acquired mutation, almost always in the JAK2 gene, in a blood stem cell. This makes the bone marrow overproduce red blood cells. It is not usually inherited and not caused by lifestyle.
How is polycythemia vera treated?
Most people have regular phlebotomy to keep their hematocrit below 45 percent and take low-dose aspirin. People at higher risk also take medicines such as hydroxyurea, interferon or ruxolitinib to lower blood counts.
Why does polycythemia vera cause itching after a shower?
Warm water is thought to trigger the release of histamine and other chemicals from overactive blood cells in the skin. This itching, called aquagenic pruritus, can be intense. Antihistamines, SSRIs, interferon or ruxolitinib often help.
What is the life expectancy with polycythemia vera?
With good treatment, many people live for decades after diagnosis, especially those diagnosed younger. Preventing clots is key. Over many years, a minority develop myelofibrosis or acute leukemia, so regular monitoring is important.
Sources
This guide was written from current patient and clinical guidance, including:
- National Comprehensive Cancer Network (NCCN): Myeloproliferative Neoplasms Guideline
- American Society of Hematology: Polycythemia Vera
- MPN Research Foundation: Polycythemia Vera
- National Organization for Rare Disorders (NORD): Polycythemia Vera
- MedlinePlus: Polycythemia vera