Polycythemia vera (PV) is a rare blood disorder. In someone with this condition, the bone marrow produces too many red blood cells. It may also produce too many white blood cells and platelets.

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PV often causes no noticeable symptoms or mild symptoms at first. They tend to become more apparent over time.

Below, we describe the different stages of PV and how healthcare providers may treat this disease.

Symptoms of PV tend to develop gradually over years.

In the early stages, the condition may cause no apparent symptoms. A healthcare provider may diagnose it following a routine blood test before any symptoms develop.

As time passes, more noticeable symptoms may occur. The disease may also cause complications such as an enlarged spleen, chest pain, a heart attack, or a stroke.

PV may eventually lead to myelofibrosis (MF). This happens when scar tissue replaces the bone marrow. Experts sometimes call this the “spent phase” of PV.

In the early stages of PV, a person may not have noticeable symptoms. Any symptoms that appear are often nonspecific.

For example, early symptoms may include:

  • fatigue
  • weakness
  • dizziness
  • a headache
  • unusual sweating, particularly at night
  • itchy skin, which may get worse after a warm bath or shower

Less common symptoms include:

  • red skin, especially on the face
  • frequent nosebleeds
  • bleeding gums
  • easy bruising
  • ringing ears
  • blurred vision
  • a burning sensation on the skin, especially of the hands and feet
  • heavy bleeding from small cuts

Also, people with PV have an increased risk of blood clots, which may develop even in the early stages. They can cause potentially life threatening complications, such as a stroke or heart attack.

PV may also cause other complications, including an enlarged spleen. The spleen filters worn-out blood cells from the body. When it becomes enlarged, it can cause a feeling of bloating or fullness in the belly.

This condition can lead to other serious complications, including more frequent infections, anemia, and increased bleeding.

As time passes, scar tissue sometimes replaces bone marrow in people with PV.

Experts call this condition MF, which stands for myelofibrosis. This is the “spent phase” of PV. It only develops in some people with the disease.

When MF occurs, the bone marrow cannot produce enough healthy blood cells.

Some symptoms of MF include:

  • fatigue
  • weakness
  • shortness of breath
  • unexplained weight loss
  • unusual sweating, particularly at night
  • itchy skin, which may get worse after a warm bath or shower
  • unusual bruising
  • bone or joint pain

People with MF may also develop an enlarged spleen or liver. This may cause discomfort and bloating, or a feeling of fullness in the belly. It can also lead to other, more serious, complications, including more frequent infections, a greater risk of bleeding, and anemia.

In rare cases, MF develops into acute myeloid leukemia.

Most cases of PV result from a change in the JAK2 gene. This gene gives the body instructions for making a protein involved in the production of blood cells.

PV causes the blood to become thicker than usual. The blood clots more easily, and it may not flow properly through blood vessels. As a result, it may carry less oxygen to the body’s tissues and organs.

Over time, these changes can cause noticeable symptoms and potentially life threatening complications.

PV advances more quickly and severely in some people than others. Not all people with PV develop MF.

A person’s outlook depends on many factors, such as:

  • their age and overall health
  • whether they have certain genetic mutations
  • whether they have high levels of white blood cells
  • the treatment they receive

Experts have not yet found a cure for PV. However, treatments for the disease may help relieve symptoms and reduce the risk of certain complications.

Treating PV

A healthcare provider may recommend a variety of treatments for PV, such as:

  • regular blood draws
  • low-dose aspirin to reduce the risk of blood clots
  • medication to limit the production of blood cells, such as:
    • hydroxyurea (Hydrea)
    • interferon-alpha (Multiferon)
    • ruxolitinib (Jakafi)

A person may also need other treatments to relieve certain symptoms or treat complications of PV.

Treating MF

If a person develops MF, the doctor may recommend regular blood transfusions, iron supplementation, and folate supplementation.

They may also prescribe a type of medication called a Janus kinase inhibitor, such as ruxolitinib (Jakafi) or fedratinib (Inrebic).

In rare cases, they may recommend a stem cell transplant. However, this treatment carries a high risk of life threatening side effects.

If a person’s spleen becomes very enlarged, the doctor may recommend surgery to remove it.

If acute myeloid leukemia develops, the doctor may prescribe chemotherapy, targeted therapy, or other treatments.

PV raises a person’s risk of potentially life threatening complications, such as a heart attack, stroke, or acute myeloid leukemia.

Early treatment is important for relieving symptoms and reducing the risk of complications. Getting treatment may help improve the quality of life and increase life expectancy.

After receiving a diagnosis of PV, a person should attend regular checkups with their healthcare provider, who may order periodic blood tests to learn how the disease is progressing. If needed, the doctor will recommend changes to the treatment plan.