Polycythemia Vera

What is polycythemia vera?

Polycythemia vera is a rare, slow-growing blood cancer in which the bone marrow — the soft, spongy tissue inside your bones that produces blood cells — makes too many red blood cells. In many cases, the bone marrow also produces too many white blood cells and platelets (small cell fragments that help blood clot). The extra cells thicken the blood, which slows blood flow and raises the risk of blood clots, strokes, and heart attacks. In medical classification systems, the condition is coded as ICD-10 D45, and it belongs to a group of disorders called myeloproliferative neoplasms, meaning conditions in which the bone marrow overproduces blood cells.

Many people first ask, “what is polycythemia vera and how serious is it?” The honest answer is that it is a chronic (long-lasting) condition that currently has no cure, but it can often be managed well for many years with regular monitoring and treatment. It is not the same as temporary increases in red blood cells caused by dehydration, smoking, or living at high altitude — those are called secondary polycythemia and have different causes and treatments.

Polycythemia vera most often affects adults over the age of 60, and it appears to be slightly more common in men than in women. It can occur in younger adults as well, though this is less common, and it is very rare in children. Because it develops slowly, some people live with it for years before it is discovered, often through a routine blood test done for another reason.

Symptoms of polycythemia vera

Polycythemia vera symptoms often develop gradually, and some people have no noticeable symptoms at all when the condition is first found. When symptoms do appear, many of them are caused by thickened blood moving sluggishly through small blood vessels, which reduces oxygen delivery to tissues.

Common polycythemia vera symptoms include:

• Headaches and a feeling of fullness or pressure in the head
• Dizziness or lightheadedness
• Itching (pruritus), often worse after a warm bath or shower — a classic and sometimes very bothersome sign
• Fatigue and weakness that does not improve with rest
• Blurred or double vision, or seeing spots
• Reddened or flushed skin, especially on the face, hands, and feet
• Burning pain, redness, or tingling in the hands or feet (a symptom doctors call erythromelalgia)
• A feeling of fullness in the upper left abdomen, caused by an enlarged spleen (the organ that filters blood)
• Unusual bleeding, such as nosebleeds, bleeding gums, or easy bruising
• Night sweats and, in some cases, unexplained weight loss
• Shortness of breath, particularly when lying down

Symptoms can differ depending on the stage of the disease. In the early, or “polycythemic,” phase, symptoms mostly relate to thick blood: headaches, itching, visual changes, and clotting problems. Over many years, some people progress to a later “spent” phase, sometimes called post-polycythemia vera myelofibrosis, in which the bone marrow becomes scarred and can no longer produce enough blood cells. In that phase, symptoms may shift toward anemia (too few red blood cells), severe fatigue, a markedly enlarged spleen, and weight loss. In a smaller number of cases, the disease can transform into acute leukemia, a faster-growing blood cancer.

Because these symptoms overlap with many other conditions, they do not confirm polycythemia vera on their own. Only blood tests and, in some cases, a bone marrow examination can establish the diagnosis.

Causes and risk factors

The most important of the known polycythemia vera causes is a change (mutation) in a gene called JAK2 (Janus kinase 2). This gene helps control how blood cells are produced. In the large majority of people with polycythemia vera, a mutation in JAK2 — most often one called JAK2 V617F — causes the bone marrow to keep making blood cells even when the body does not need them. A smaller group of patients carries a related mutation in a different part of the same gene.

Importantly, this mutation is almost always acquired, meaning it develops during a person’s lifetime rather than being inherited from a parent. Polycythemia vera is therefore not usually passed directly from parents to children, although in rare families a tendency toward myeloproliferative conditions may run in the bloodline. Doctors do not know exactly why the JAK2 mutation occurs in some people and not others, and there is no known way to prevent it.

Recognized risk factors include:

• Age: the condition is most often diagnosed after age 60, though it can appear earlier
• Sex: it is somewhat more common in men
• Family history: a small increase in risk if a close relative has a myeloproliferative neoplasm

Lifestyle factors such as diet, exercise, or stress are not known to cause polycythemia vera. It is also worth repeating that secondary polycythemia — extra red blood cells caused by chronic low oxygen (for example, from lung disease, sleep apnea, or heavy smoking) — is a different condition with a different cause and is not a cancer.

Diagnosis

Polycythemia vera diagnosis usually begins when a routine blood test shows unusually high red blood cell counts. To confirm the condition and rule out other explanations, doctors typically use a combination of blood tests, genetic testing, and sometimes a bone marrow biopsy. Internationally accepted diagnostic criteria, such as those from the World Health Organization, guide this process.

Tests your doctor may order include:

• Complete blood count (CBC): measures red blood cells, white blood cells, and platelets. In polycythemia vera, hemoglobin (the oxygen-carrying protein in red blood cells) and hematocrit (the percentage of blood made up of red blood cells) are typically elevated.
• JAK2 mutation testing: a blood test that looks for the gene change found in the vast majority of people with this condition. A positive result strongly supports the diagnosis.
• Erythropoietin (EPO) level: erythropoietin is a hormone made by the kidneys that signals the bone marrow to produce red blood cells. In polycythemia vera, the EPO level is usually low, because the marrow is overproducing cells on its own. In secondary polycythemia, EPO is often normal or high.
• Bone marrow biopsy: a procedure in which a small sample of bone marrow is taken, usually from the hip bone, under local anesthetic. Under the microscope, the marrow in polycythemia vera typically shows increased production of all blood cell lines.
• Imaging, such as abdominal ultrasound: may be used to check whether the spleen or liver is enlarged.

Doctors also review your medical history and may test for other causes of high red blood cell counts — such as lung disease, sleep apnea, kidney conditions, or smoking — before confirming the diagnosis. Because polycythemia vera is uncommon and its management is specialized, diagnosis and long-term care are usually led by a hematologist, a doctor who specializes in blood disorders. At Acibadem, for example, this condition is evaluated and managed within the Hematology Department.

Treatment options

There is currently no cure for polycythemia vera apart from, in very selected cases, a stem cell transplant, which is rarely used because of its risks. Instead, polycythemia vera treatment focuses on two main goals: reducing the risk of dangerous blood clots and relieving symptoms. Treatment is tailored to each person based on age, clot history, blood counts, and overall health. An overview of how this condition is approached can be found on the polycythemia vera treatment page.

Phlebotomy (blood removal)

The most common first-line treatment is phlebotomy, a procedure similar to donating blood, in which a unit of blood is removed from a vein. This directly lowers the number of red blood cells and thins the blood. Phlebotomy is usually repeated at intervals until the hematocrit reaches a target set by your doctor, and then performed as needed to keep it there.

Low-dose aspirin

Many patients are advised to take low-dose aspirin daily to reduce the risk of clots and to ease symptoms such as burning pain in the hands and feet. Aspirin is not suitable for everyone — for example, people with significant bleeding problems — so this decision is always individualized by your doctor.

Medications that lower blood cell production

If phlebotomy and aspirin are not enough, or if a person is considered at higher risk of clots (for example, because of older age or a previous clot), doctors may add cytoreductive medication — drugs that slow the bone marrow’s overproduction of cells. Options may include:

• Hydroxyurea: an oral medication that reduces blood cell production and is often the first-choice drug therapy.
• Interferon-based therapy: injectable medications that can control blood counts and are sometimes preferred in younger patients or during pregnancy planning, under specialist guidance.
• JAK inhibitors, such as ruxolitinib: targeted drugs that block the overactive JAK2 signaling pathway. They may be used when other treatments do not work well or are not tolerated, and they can also help with itching and an enlarged spleen.

Symptom-directed treatment

Itching can be one of the most distressing symptoms, and doctors may suggest antihistamines, certain antidepressant medications that also relieve itch, light therapy, or adjustments to bathing habits (such as cooler water). Medications may also be used to manage gout-like joint pain caused by high uric acid, which can occur when many blood cells are broken down.

Monitoring and supportive care

Even when treatment is going well, regular blood tests and follow-up visits are essential to keep the hematocrit in the target range and to watch for changes in the disease over time. Managing cardiovascular risk factors — controlling blood pressure, treating diabetes, stopping smoking, and staying physically active as advised — is an important part of care, because these factors add to the clotting risk. Surgery is not a treatment for polycythemia vera itself; however, in advanced disease, removal of a severely enlarged spleen is occasionally considered, and this decision is weighed carefully because of its risks.

Living with polycythemia vera and outlook

Polycythemia vera is a chronic condition, and most people live with it for many years. With careful monitoring and treatment to keep blood counts controlled, many patients maintain a good quality of life and a life expectancy that can extend for decades after diagnosis, although outcomes vary from person to person and no doctor can guarantee an individual result. The most serious short-term risk is blood clotting, which is why keeping the hematocrit within target and attending follow-up appointments matter so much.

Over the long term, a minority of patients progress to myelofibrosis (scarring of the bone marrow) or, less commonly, to acute leukemia. Regular specialist follow-up allows these changes to be detected early if they occur.

Day-to-day, many people with polycythemia vera find the following helpful, alongside their medical treatment:

• Staying well hydrated, since dehydration thickens the blood further
• Avoiding smoking, which raises clotting risk
• Staying physically active within your doctor’s guidance, and avoiding long periods of immobility (for example, moving regularly on long flights)
• Using cooler water for bathing and gentle skin care to reduce itching
• Protecting hands and feet from extreme temperatures, which can trigger burning pain
• Telling every healthcare provider — including dentists and surgeons — about your diagnosis before any procedure

Living with a chronic blood cancer can also be emotionally demanding. Support from family, patient organizations, or counseling can help, and it is reasonable to raise anxiety or low mood with your care team.

Frequently asked questions

What is polycythemia vera in simple terms?

Polycythemia vera is a slow-growing blood cancer in which the bone marrow makes too many red blood cells, and often too many white blood cells and platelets as well. The extra cells thicken the blood, which can cause headaches, itching, and fatigue, and raises the risk of blood clots. It is usually caused by an acquired change in a gene called JAK2 and is most often diagnosed in adults over 60.

Can polycythemia vera be cured?

At present there is no widely available cure for polycythemia vera. A stem cell transplant can potentially cure the disease, but it carries significant risks and is reserved for rare, carefully selected situations. For most people, treatment focuses on controlling blood counts, preventing clots, and relieving symptoms — and with this approach, the condition can often be managed successfully for many years.

How serious is polycythemia vera?

It is a serious diagnosis because untreated thick blood can lead to strokes, heart attacks, and other clot-related problems, and because in some people the disease can progress over time. However, it is also one of the more manageable blood cancers. With regular monitoring and treatment, many patients live for decades after diagnosis. Your own outlook depends on factors such as your age, clot history, and how well your blood counts respond to treatment, so it is best discussed with your hematologist.

What are the early symptoms of polycythemia vera?

Early polycythemia vera symptoms are often vague: headaches, dizziness, tiredness, blurred vision, and flushed or reddened skin. Itching after a warm bath or shower is a particularly characteristic early sign. Some people have no symptoms at all, and the condition is discovered by chance on a routine blood test. Because these symptoms overlap with many everyday conditions, only blood testing can determine the cause.

Is polycythemia vera hereditary?

In the vast majority of cases, no. The JAK2 gene mutation that drives the disease is acquired during a person’s lifetime and is not present in the reproductive cells passed to children. A slightly increased tendency toward myeloproliferative disorders has been observed in some families, but polycythemia vera is not considered a directly inherited condition, and routine testing of family members is not usually needed unless a doctor advises otherwise.

How is polycythemia vera diagnosed?

Polycythemia vera diagnosis typically involves a complete blood count showing elevated red blood cells, a genetic blood test for the JAK2 mutation, and a measurement of the hormone erythropoietin, which is usually low in this condition. In many cases, a bone marrow biopsy is performed to confirm the diagnosis and assess the marrow. Doctors also rule out other causes of high red blood cell counts, such as lung disease or sleep apnea, before confirming the condition.

Can you live a normal life with polycythemia vera?

Many people can live a largely normal life, especially when the condition is diagnosed before complications occur and blood counts are kept well controlled. Ongoing treatment — often phlebotomy, low-dose aspirin, and sometimes medication — plus regular follow-up visits are usually part of daily life. Some symptoms, such as fatigue or itching, may persist and need active management, but work, travel, and physical activity are often possible with your doctor’s guidance.

When to see a doctor

If you have persistent unexplained symptoms such as headaches, itching after warm showers, fatigue, or flushed skin, it is reasonable to see a doctor and ask about blood testing. If you have already been diagnosed with polycythemia vera, keep your scheduled follow-up appointments even when you feel well, because clotting risk can rise without obvious warning.

Seek emergency medical care immediately if you experience any of the following red-flag signs, which may indicate a blood clot or serious bleeding:

• Sudden weakness, numbness, or drooping on one side of the face or body, trouble speaking, or sudden confusion — possible signs of a stroke
• Chest pain or pressure, especially with shortness of breath, sweating, or pain spreading to the arm or jaw — possible signs of a heart attack
• Sudden shortness of breath or sharp chest pain when breathing — possible signs of a clot in the lungs
• Painful swelling, warmth, or redness in one leg — possible signs of a deep vein clot
• Sudden severe abdominal pain, which can indicate a clot in the veins of the abdomen
• Sudden loss of vision or severe visual disturbance
• Heavy or uncontrolled bleeding, blood in vomit or stool, or black, tarry stools
• A sudden, severe headache unlike any you have had before

These symptoms always warrant urgent evaluation, whether or not you have been diagnosed with polycythemia vera. Prompt treatment of clots and bleeding can be lifesaving.