Polycythemia Vera (POL-e-si-THE-me-ah VE-ra), or PV, is a rare blood disease in which the body manufactures too many red blood cells. These extra red blood cells make the blood thicker than normal. The thickened blood flows more slowly through the small blood vessels and can form clots, which can cause a heart attack or stroke.
Blood cells are formed in the bone marrow, which is the soft tissue inside bones. In addition to red blood cells, blood contains two other types of cells: white blood cells to help fight infection and platelets to help the blood clot. In individuals with PV, the bone marrow 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 but with shallow indents rather than 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.
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, 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, thickening of the blood slows down the flow of blood to all parts of the body. Clots form more easily, potentially blocking blood flow through arteries or veins. The slower flow of blood means that organs do not receive enough oxygen. The shortage of oxygen can lead to angina, congestive heart failure, and gout. Slower blood flow also deprives the arms, legs, lungs, and eyes of the oxygen they need to perform normally. This can cause headaches, dizziness, itching, and problems with vision, such as blurred or double vision.
PV may also cause 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 the 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. 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.