Polycythemia is an increase of red blood cells in the body. The extra cells cause the blood to be thicker, and this, in turn, increases the risk of other health issues, such as blood clots.

Polycythemia can have different causes, each of which has its own treatment options. The treatment of polycythemia involves treating any underlying conditions, if possible, and finding ways to bring blood cell levels down.

In this article, learn more about the causes of polycythemia, as well as the symptoms and treatment options.

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Polycythemia is a condition characterized by an abnormal rise in red blood cells in the body. This increase manifests through increased levels of hemoglobin above the normal levels for the person’s age and gender.

According to the Red Cross, normal hemoglobin levels for males assigned at birth (MAAB) are 13.5-17.5 grams per deciliter (g/dL). For females assigned at birth (FAAB), the range is 12.0-15.5 g/dL.

Another way to look at it is by looking at the percentage that red blood cells make up in the blood. In adult MAABs, this should be 41-50%, whereas in FAABs the range is 36%-44%.

The ranges for children, older adults, and people who are pregnant vary. The ranges can also vary based on geographic location, ethnicity, and altitude. In newborns, doctors will suspect polycythemia if their values are 65% and above 22 g/dL

There are two types of polycythemia, which have different causes.

Primary polycythemia

Primary polycythemia is also called polycythemia vera (PV).

PV is a rare, slow-growing blood cancer that is a type of condition known as a myeloproliferative neoplasm. PV causes the bone marrow to create excess precursor blood cells that develop and function abnormally, leading to the production of too many red blood cells.

A person with PV may also have increased numbers of other blood cells, such as white blood cells or platelets.

Secondary polycythemia

Secondary polycythemia can occur if the increase in red blood cells is not due to the myeloproliferative disease of PV.

The overproduction of blood cells in secondary polycythemia is limited to the red blood cells.

Causes of secondary polycythemia include:

  • being at a very high altitude
  • obstructive sleep apnea
  • certain types of tumor
  • heart or lung disease that causes a low oxygen level in the body

Risk factors

Some people may be more at risk than others of primary polycythemia. The National Center for Advancing Translational Sciences notes that most cases of PV appear as a person ages, usually around the age of 60 years. They also note that it is more common in men than in women.

PV is not necessarily hereditary, and most people with the disease do not have a family history of PV. However, there appears to be a connection to a certain genetic mutation.

The Leukemia & Lymphoma Society notes that almost all individuals with PV have a mutation in the Janus kinase 2 (JAK2) gene. However, the precise role that it plays in the condition is still unclear.

Other gene mutations, such as that of the TET2 gene, may also have an association with this condition. Most of the time, these genes are not hereditary, but in some rare cases, they may pass from a parent to their child in the sperm or egg.

Anyone with a family history of PV may still wish to see a doctor for an evaluation.

It is not uncommon for a person to have polycythemia and be unaware of it. Symptoms tend to build very slowly over time.

Having too many red blood cells thickens the blood, which makes healthy blood flow more difficult. It can also increase a person’s risk of blood clots. This risk is especially high if a person with PV has an excess of both red blood cells and platelets.

A doctor may discover the condition during a routine blood examination or when following up on another condition.

The symptoms of PV may become more apparent over time. More common symptoms include:

  • dizziness or vertigo
  • headaches
  • excessive sweating
  • itchy skin
  • ringing in the ears
  • blurred vision
  • fatigue
  • reddish or purplish skin on the palms, earlobes, and nose
  • bleeding or bruising
  • a burning sensation in the feet
  • abdominal fullness
  • frequent nosebleeds
  • bleeding gums

Without treatment, people with PV may also be more likely to experience complications, such as:

  • enlarged spleen
  • blood clots
  • angina
  • stroke
  • peptic ulcers
  • heart disease
  • gout
  • other blood disorders, such as myelofibrosis or leukemia

If doctors suspect that a person has polycythemia, they will order several tests to help identify the underlying issue.

Blood tests

Blood tests, such as a complete blood count, will reveal any increase in red blood cells or hemoglobin in the bloodstream, as well as any abnormal levels of platelets and white blood cells. If PV seems possible, a doctor will order more specific blood tests.

Bone marrow biopsy

If necessary, the doctor may also want to remove some bone marrow on which to perform tests in a lab.

A bone marrow biopsy involves taking a small sample of the bone marrow with a needle for examination under a microscope.

Genetic tests

Although genetic causes of PV are rare, doctors may also want to analyze the person’s bone marrow for genetic mutations that have links to PV.

They may also recommend examining cells in the blood for JAK2 mutation.

Treatment for polycythemia will depend on the underlying cause of the condition.

In people with secondary polycythemia resulting from causes such as obstructive sleep apnea, treating the underlying cause should help resolve the high red blood cell count.

PV, however, is a chronic condition that has no known cure. The treatment for PV aims to manage the condition by reducing both the red blood cell count and the risk of complications, such as blood clots. If the platelet count is too high, there are ways to treat this as well.

Treatment options for PV can include:


To help manage the condition, doctors will look to reduce the red blood cell count through a process called phlebotomy, which manually removes blood through one of the veins.

Depending on the individual case, doctors will recommend removing a certain amount of blood at set intervals to get the red blood cell count closer to normal levels.

Drugs to reduce blood cells

Sometimes, phlebotomy is not enough to control blood cell growth. Doctors may then recommend myelosuppressive drugs to help control blood cell counts.

These drugs include hydroxyurea (Hydrea), which suppresses the bone marrow to keep it from producing as many blood cells.

JAK2 inhibitors

In cases where a person does not respond well to other medications, doctors may recommend drugs that inhibit the JAK2 enzyme, which the JAK2 gene is responsible for producing. These include ruxolitinib (Jakafi).

Other medications

Doctors will also often recommend other drugs to help control symptoms. These include aspirin and antihistamines. Taking low-dose aspirin helps reduce the risk of clotting in many people with PV, and it may also alleviate troubling symptoms, such as headaches. Doctors may recommend antihistamine drugs to help relieve itchiness.

Polycythemia can be managed with treatment. However, certain complications can turn into a life-threatening condition.

Complications related to polycythemia are usually excessive bleeding or blood clots in either the arteries or the veins. This can become life-threatening if not immediately treated.

In about 5% of cases, polycythemia may progress to difficult-to-treat leukemia.

Determining the underlying type of polycythemia helps doctors know how best to treat or manage the issue. If treatment is possible, the person should make a full recovery.

In cases of PV, treatment will focus on managing the condition and symptoms, as there is currently no cure. However, in most cases, the person will have a normal or nearly normal quality of life, and doctors can effectively manage the condition for a very long time.

That said, having complications can affect a person’s outlook. Some risk factors that can worsen the outlook include a history of blood clots, higher white blood cell counts, or the presence of immature forms of red and white cells in the blood. The latter two factors may indicate cancer

Polycythemia is an increase in the number of red blood cells in the body. Doctors may discover it as part of a routine blood check, or they might diagnose it once the person starts experiencing symptoms.

PV is a chronic condition with no known cure. However, effective treatment can help sufficiently manage the disease and its symptoms.

Anyone who has symptoms or a family history of polycythemia vera should see a doctor for a diagnosis.