What Is Polycythemia Vera?

Polycythemia vera (POL-e-si-THE-me-ah VE-ra), or PV, is a rare blood disease in which your body makes too many red blood cells. These extra red blood cells make your blood thicker than normal. The thickened blood flows more slowly through your small blood vessels and can form clots. These clots can cause heart attack and stroke.

Blood cells are formed in your bone marrow—the soft tissue inside bones. In addition to red blood cells, your blood contains two other types of cells: white blood cells to help fight infection and platelets to help your blood clot. If you have PV, your bone marrow produces too many red blood cells, but it also can make too many white blood cells and platelets.

Red blood cells also are called RBCs or erythrocytes (eh-RITH-ro-sites). Normal red blood cells look like doughnuts without holes in the center and have an average lifespan of 120 days. Red blood cells contain hemoglobin (HEE-muh-glow-bin), an iron-rich protein that gives blood its red color and carries oxygen to the body. Red blood cells also remove carbon dioxide, a waste product, from cells and carry it to the lungs to be exhaled.

Important General Information

PV is a rare, chronic disease that can be fatal if not diagnosed and treated. The cause of PV is not known. It develops slowly and may not produce symptoms for many years. Sometimes, your symptoms can be vague and nonspecific. Many people find out they have PV from blood tests done for other reasons. It is more common in adult males 60 years or older. It is very rare in people younger than 20 years.

With PV, thicker than normal blood slows down the flow of blood to all parts of your body. Clots can form more easily, which can block blood flow through arteries or veins. The slower flow of blood means your organs don’t receive enough oxygen. The shortage of oxygen can lead to angina, congestive heart failure, and gout. Slower blood flow also deprives your arms, legs, lungs, and eyes of the oxygen they need to perform normally. This can cause headaches, dizziness, itching, and problems with your vision, such as blurred or double vision.

PV may also cause you to develop stomach ulcers and kidney stones.

A small number of people with PV may develop myelofibrosis (MY-e-lo-fi-BRO-sis), a condition in which your bone marrow is replaced by fibrous (scar) tissue. The abnormal bone marrow cells may begin to grow out of control. This abnormal growth can lead to acute myelogenous (my-e-LOJ-e-nus) leukemia (AML), a disease that worsens very quickly. In AML, too many immature white blood cells are found in the blood and bone marrow.

Outlook

PV is a serious illness that can lead to death if it is not treated.

PV can be controlled with treatment, but no cure exists. If you think you or someone you know might have PV, it is important to talk to your doctor about it. Some people with PV need only minimal care. Others will need more intensive treatment. Treatment can control PV and lessen the risk of blood clots, heart attack, and stroke that can result from the disease.

September 2008