Symptoms and Causes of Essential Thrombocythemia

A Rare Condition Causing Excessive Blood Clotting

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Essential thrombocythemia (ET) is a rare form of blood cancer that causes the bone marrow to produce too many platelets (the blood cells responsible for clotting). This excessive production can cause the inappropriate formation of blood clots that can block blood vessels, referred to as thrombosis.

ET belongs to a larger group of blood cancers called myeloproliferative neoplasms that cause the excessive production of blood cells. The diagnosis is largely based on the exclusion of all other possible causes. Not all cases of ET require treatment, but those that may benefit from anticoagulants ("blood thinners") and other drugs that counter the effects of ET.

This article looks at the symptoms and causes of essential thrombocythemia, including how this rare condition is diagnosed and treated. It also describes possible complications of ET and the current survival rates for those diagnosed with the disease.

Blood Clots
Science Photo Library - STEVE GSCHMEISSNER / Getty Images

Essential Thrombocythemia Symptoms

The symptoms of ET vary depending on where it is in the body a blood clot forms. Blood clots caused by ET can form anywhere but most commonly develop in the deep veins of the leg, lungs, brain, and heart.

Abnormal bleeding is a common feature of ET. This is because the protein responsible for sticking blood cells together and forming clots, called the von Willebrand factor, gets spread too thin even as platelets are overproduced. When this happens, bleeding can spontaneously occur in the gut, under the skin, or in the nose, mouth, and gums.

Symptoms of essential thrombocythemia may include:

  • Headache
  • Fatigue
  • Dizziness or lightheadedness
  • Weakness
  • Fainting
  • Chest pains
  • Blurred vision
  • Nosebleeds
  • Bleeding gums
  • Numbness, burning, or tingling in hands or feet
  • Easy bruising
  • Purplish discoloration of the lower legs
  • Black or tarry stools
  • Abnormal vaginal bleeding

Complications of Essential Thrombocythemia

The formation of blood clots can sometimes be serious and potentially lead to heart attack, stroke, transient ischemic attack (a "mini-stroke"), or digital ischemia (loss of blood flow to a finger or toe).

An enlarged spleen (splenomegaly) is also seen in up to 20% of cases due to the obstruction of blood circulation, leading to a swollen abdomen, bloating, and a loss of appetite.

Additional complications include an increased risk of pregnancy loss and other complications of pregnancy in people with ET.

In rare cases, ET can cause a stroke, heart attack, deep vein thrombosis (DVT), or a pulmonary embolism, usually in people with underlying risk factors for these diseases.

People with ET also have an increased risk of developing other blood cancer like myelodysplastic syndromes (MDS) or acute myeloid leukemia (AML).

What Causes Essential Thrombocythemia?

Essential thrombocythemia is one of six myeloproliferative neoplasms (MPNs). MPNs are a rare group of blood cancers that cause the overproduction of red blood cells (erythrocytes), white blood cells (leukocytes), or platelets (thrombocytes) by the bone marrow. 

The prefix "myelo" refers to the bone marrow, while "neoplasm" describes growth that is abnormal and out of control.

It is unclear what causes MPNs like essential thrombocythemia, although genetics is thought to play a central role.

What is known is that MPNs occur when immature blood cells (called blast cells) develop sudden genetic changes (called somatic mutations) that cause them to grow abnormally. Around 55% of cases involve a genetic mutation known as Janus kinase 2 (JAK2). Other gene mutations, called MPN and CALC, have also been implicated.

ET is exceptionally rare, affecting fewer than three out of 100,000 people each year. Males and females of all racial or ethnic backgrounds are equally affected, although ET tends to be seen more in adults over 60.

How Is Essential Thrombocythemia Diagnosed?

Essential thrombocythemia is often spotted during a routine blood exam in persons who either have no symptoms or vague, nonspecific symptoms (such as fatigue or a headache). Any blood count of over 450,000 platelets per microliter is considered a red flag. Those over a million per microliter are associated with a higher risk of abnormal bruising or bleeding.

A physical exam may reveal a spleen enlargement characterized by pain or fullness in the left upper abdomen that may spread to the left shoulder. Genetic testing may also be performed to detect the JAK2, CALC, and MPL mutations.

The diagnosis of ET is largely exclusionary, meaning that any other cause for the high platelet count must be first excluded to make a definitive diagnosis.

Other conditions associated with a high platelet count include:

How Is Essential Thrombocythemia Treated?

The treatment of essential thrombocythemia depends largely on how elevated the platelet count is as well as the likelihood of complications. Not all people with ET require treatment. Some simply need to be monitored to ensure the condition doesn’t worsen.

If needed, treatment may involve a daily low-dose aspirin for those at high risk of bleeding or vasomotor symptoms (like flushing or hot flashes).

If aspirin fails to provide relief, other drugs may be considered, including:

  • Hydroxyurea: A chemotherapy drug that lowers platelet count
  • Busulfex (busulfan): Another chemotherapy drug used for people who can’t take hydroxyurea
  • Agrilyn (anagrelide): An anticoagulant drug that lowers platelet counts and helps reduce the risk of heart attack or stroke
  • Interferon alfa: A drug that keeps platelets from dividing and multiplying
  • Jakafi (ruxolitinib): A JAK2 inhibitor used when hydroxyurea and other drug options fail to provide relief

In an emergency, plateletpheresis (a process in which blood is separated into its individual components) may be performed to quickly reduce platelet counts. This is a short-term solution that is typically followed by treatment with platelet-reducing drugs like hydroxyurea or Agrilyn.

What is the life expectancy of a person with essential thrombocythemia?

Because of the effectiveness of current treatments, the life expectancy of someone with essential thrombocythemia is more or less equal to that of the general population. The median survival from the time of diagnosis (typically around age 60) is 20 years.

Summary

Essential thrombocythemia is a rare blood cancer that causes the excessive production of platelets. Symptoms range from nosebleeds and abnormal vaginal bleeding to rare but potentially life-threatening complications like heart attack or stroke.

The diagnosis is largely based on the exclusion of all other causes, although genetic testing can help support the diagnosis. ET doesn't always need to be treated, but drugs are available that help reduce platelet counts and clotting should symptoms develop.

5 Sources
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  1. Tefferi A, Barbui T. Polycythemia vera and essential thrombocythemia: 2021 update on diagnosis, risk‐stratification and management. Am J Hematol. 2020;95(12):1599-1613. doi:10.1002/ajh.26008

  2. National Institutes of Health Genetic and Rare Diseases Information Center. Essential thrombocythemia.

  3. Andriani A, Latagliata R, Anaclerico B, et al. Spleen enlargement is a risk factor for thrombosis in essential thrombocythemia: evaluation on 1,297 patients. Am J Hematol. 2016;91(3):318-321. doi:10.1002/ajh.24269

  4. Accurso V, Santoro M, Mancuso S, et al. The essential thrombocythemia in 2020: what we know and where we still have to dig deep. Clin Med Insights Blood Disord. 2020;13:263485352097821. doi:10.1177/2634853520978210

  5. Jiang H, Jin Y, Shang Y, et al. Therapeutic plateletpheresis in patients with thrombocytosis: gender, hemoglobin before apheresis significantly affect collection efficiency. Front Med. 2021;8:762419. doi:10.3389/fmed.2021.762419

By Mary Kugler, RN
Mary Kugler, RN, is a pediatric nurse whose specialty is caring for children with long-term or severe medical problems.