Polycythemia vera

Polycythemia vera is a rare type of blood cancer where too many red blood cells are formed in the bone marrow, which is the soft, spongy material at the center of your bones. The high red blood cell count thickens the blood, which can cause serious complications if not treated quickly once identified. Thickened blood can potentially lead to complications such as blood clots, strokes, or heart attacks.

Polycythemia vera is treated by doctors who specialize in blood disorders called hematologists and may also be treated by doctors who specialize in cancer called oncologists. Penn Medicine's Blood Cancer Program is an internationally recognized leader in the diagnosis, treatment, and management of cancer and blood disorders like polycythemia vera.

Polycythemia vera happens slowly, and patients sometimes go years without symptoms. The condition is often detected through tests done for another reason. Symptoms are different for everyone but may include: 

• Bleeding gums or nosebleeds  
• Blind spots, blurred vision, or double vision  
• Bloating after eating  
• Bruising  
• Difficulty focusing  
• Dizziness  
• Fatigue (low energy)  
• Headache  
• High blood pressure   
• Itchy skin  
• Joint swelling  
• Night sweats  
• Numbness in your hands, arms, feet, or legs  
• Ringing in your ears  
• Trouble breathing while lying down  
• Weakness

Most patients with polycythemia vera have experienced a genetic mutation that causes a change in blood cell production. The change, which happens over many years, causes your bone marrow to make too many red blood cells. The cause of the genetic change is unknown, but it doesn’t tend to be passed down through families.

The specific mutation associated with polycythemia vera occurs in a gene called Janus kinase 2, commonly referred to as JAK2. Normally, the JAK2 gene helps regulate the production of blood cells. However, in polycythemia vera, a mutation known as JAK2 V617F is often present. This mutation causes the JAK2 protein to be constantly activated, leading to uncontrolled growth and division of blood cells, particularly red blood cells.

Other genetic mutations and environmental factors may also contribute to the development of polycythemia vera, but the JAK2 mutation is the most commonly identified genetic abnormality associated with this condition. 

Though it can happen at any age, polycythemia vera is more common in adults 50 to 75 years old, and to those assigned male at birth. There are several complications associated with polycythemia vera, including the following:

• Blood clots: The increase in blood thickness and abnormalities in platelets increases the risk of blood clots that could cause a stroke or heart attack, or block the blood flow to your lungs, legs, or abdomen.
• Blood disorders: Polycythemia vera can lead to other blood diseases in rare cases.
• Enlarged spleen: The extra blood cells can make your spleen work harder than normal, causing it to grow larger, which can lead to more frequent infections.
• Other conditions: Having a high red blood cell count can cause open sores in the stomach’s lining, intestines, or esophagus. It can also cause gout, which is inflammation in your joints. 

Talk with your Penn Medicine provider if you have any questions or concerns.

Team approach to exceptional care

Our hematologists and medical oncologists work side-by-side with other treatment team members, including physicians and nurses who specialize in surgical oncology, radiology, and pathology, to give you the best possible outcome. In addition, thanks to the care provided by our specialists, Penn Medicine's Abramson Cancer Center was rated by the National Cancer Institute as an “exceptional” cancer center that is recognized for its leadership, resources, and research related to cancer care.