Medically Reviewed By William C. Lloyd III, MD, FACS
Was this helpful?

What is polycythemia?

Polycythemia is a blood condition in which the bone marrow makes excess blood cells, primarily red blood cells, but also platelets and white blood cells. The extra cells cause a thickening of the blood, which increases the risk of blood clotting, in turn potentially causing strokes, heart attacks, and other complications. While the exact cause of polycythemia is not known, genetic changes are thought to be related to its development.

Genetic polycythemia, referred to as polycythemia vera, develops slowly and is generally seen in older adults. It is rare in young adults and children. Although it is the result of genetic mutations or changes in particular genes, these genetic changes are acquired during an individual’s lifetime and are generally not passed from parents to their children. Polycythemia is more common in adults over 60 years of age, and about one in every 200,000 people is diagnosed each year with the condition (Source: NHLBI).

In the early stages of polycythemia, symptoms may be mild and include flushed face, dizziness, and impaired senses. In more severe cases, thrombosis (blood clotting) may occur, leading to severe symptoms.

In secondary polycythemia, long-term oxygen deprivation, such as from chronic smoking or long periods spent at high altitudes, causes increased production of red blood cells and resultant blood thickening. This form of polycythemia often resolves once the cause of oxygen deprivation is addressed. In all cases of polycythemia, treatment by periodic blood draws or medications to reduce the number of blood cells is generally effective, although there is no cure for the condition.

While polycythemia is rare, generally treatable, and usually mild, serious complications such as heart attack or stroke can occur if left untreated. Seek immediate medical care (call 911) for any sudden symptoms of heart attack or stroke, such as sudden numbness, weakness, confusion, vision problems, or chest pain.

Polycythemia may also lead to less severe symptoms, such as difficulty breathing when lying down or excessive bleeding. Seek prompt medical care if these symptoms persist, as early diagnosis and intervention are critical to preventing more severe symptoms.

What are the symptoms of polycythemia?

Symptoms of polycythemia include symptoms related to excessive thickening of the blood, such as reddened face, bleeding of the gums, dizziness, and itchiness. Polycythemia can also affect the eyes and ears, leading to blurred vision or tinnitus. In more serious cases of polycythemia, thrombosis (clotting) can develop, leading to heart attack or stroke.

Common symptoms of polycythemia

You may experience polycythemia symptoms daily or just once in a while. At times, any of these symptoms can be severe:

Serious symptoms that might indicate a life-threatening condition

In some cases, the complications of polycythemia, including heart attack and stroke, can be life threatening. Seek immediate medical care (call 911) if you, or someone you are with, have any of these life-threatening symptoms including:

  • Confusion or loss of consciousness for even a brief moment
  • Difficulty breathing
  • Loss of balance
  • Loss of vision or changes in vision
  • Numbness or weakness of the limbs or face
  • Severe headache
  • Sudden chest or shoulder discomfort

What causes polycythemia?

The exact causes of polycythemia are not known. There is evidence, however, that mutations (changes) in specific genes are related to the development of the disease. These mutations occur during an individual’s lifetime and are not passed on from parents to their children. Only in very rare cases is polycythemia inherited.

A second type of polycythemia, called secondary polycythemia, occurs when the body is deprived of oxygen for extended periods of time, such as in heavy smokers. In secondary polycythemia, the body overproduces a hormone called erythropoietin. Erythropoietin is in charge of regulating the body’s supply of red blood cells. When overproduced, erythropoietin can cause thickening of the blood, leading to the symptoms of polycythemia. Often, this type of polycythemia can be treated by addressing the cause of oxygen shortage.

Causes of secondary polycythemia

Secondary polycythemia can occur with a number of conditions that result in lowered oxygen levels in the blood including:

  • Heavy smoking
  • Residing at high altitude
  • Severe heart or lung disease that limits oxygen delivery to tissues

What are the risk factors for polycythemia?

A number of factors increase the risk of developing polycythemia. Not all people with risk factors will get polycythemia. Risk factors for polycythemia include:

  • Age over 60 years
  • Excessive smoking
  • Male gender
  • Prolonged exposure to low oxygen levels (such as due to smoking)

How is polycythemia treated?

Polycythemia is treated by thinning the blood to keep clots from forming. This can be performed by periodic blood draws to reduce red blood cell count. In some cases, medications may be administered to suppress the bone marrow and reduce blood cell counts, including hydroxyurea and interferon. Aspirin may also be used to prevent blood clots, although this is less common due to an increased risk of stomach bleeding.

What are the potential complications of polycythemia?

While the progression of polycythemia is generally slow and most patients do not experience complications, there can be rare incidences of problems related to polycythemia. People with polycythemia are at increased risk of developing blood clots, which can lead to strokes and heart attacks if untreated. Furthermore, the bone marrow disturbances of polycythemia can lead to myelofibrosis (scarring of the bone marrow) or, in very rare instances, leukemia. Such complications can be life-threatening and should be treated immediately.

You can help minimize your risk of serious complications by following the treatment plan you and your health care professional design specifically for you. Complications of polycythemia include:

  • Blood clots (thrombosis)
  • Enlarged spleen (splenomegaly)
  • Gastrointestinal bleeding
  • Gout (type of arthritis caused by a buildup of uric acid in the joints)
  • Heart failure
  • Leukemia (cancer of the blood or bone marrow)
  • Myelofibrosis (scarring of the bone marrow)
  • Peptic ulcers
Was this helpful?
Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Jan 15
View All Blood Conditions Articles
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
  1. Polycythemia vera. National Heart, Lung, and Blood Institute Diseases and Conditions Index. http://www.nhlbi.nih.gov/health/dci/Diseases/poly/poly_whatis.html
  2. Polycythemia vera. PubMed Health. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001615/
  3. Spivak JL. The optimal management of polycythaemia vera. Br J Haematol 2002; 116:243.
  4. Bope ET, Kellerman RD (Eds.) Conn’s Current Therapy. Philadelphia: Saunders, 2013.
  5. Domino FJ (Ed.) Five Minute Clinical Consult. Philadelphia: Lippincott Williams & Wilkins, 2013.