What Are Myeloproliferative Disorders?

Myeloproliferative disorders include several different conditions that are characterized by excess production of blood cells in the body. They differ based on which type of blood cell is overproduced—red blood cells (carry oxygen from the lung to tissues), platelets (help the blood to clot), or white blood cells (help the body fight infection).

The symptoms, causes, and treatments depend on the type and severity of the disorder. Diagnosis of each condition involves a similar process, and usually includes a blood test, and possibly a bone marrow biopsy. This article will help you understand your risks and what to expect if you have a myeloproliferative disorder. 

Types of Myeloproliferative Disorders

Sometimes myeloproliferative disorders are described as myeloproliferative neoplasms. These conditions are rare, and they typically occur during adulthood, although they can occur during childhood as well.

The types of myeloproliferative disorders include:

• Polycythemia vera: An overproduction of red blood cells
• Essential thrombocythemia: An overproduction of platelets 
• Primary myelofibrosis: Excess fibrous tissue in the bone marrow 
• Chronic myelogenous leukemia (also called myeloid leukemia): An overproduction of immature granulocyte white blood cells
• Chronic eosinophilic leukemia: An overproduction of eosinophil white blood cells, which are involved in allergic reactions and fighting parasitic infections
• Chronic neutrophilic leukemia: An overproduction of neutrophil white blood cells, which are involved in fighting infections

These conditions can cause similar symptoms, including fevers and fatigue, although each has its own set of effects and complications. They each have a separate cause, and while there are some similar treatments, they each are also treated with specific therapies. 

Myeloproliferative Disorder Symptoms

Often, myeloproliferative disorders cause generalized weakness and persistent tiredness. They might not cause symptoms at early stages, and the obvious effects can begin during late stages of the disease. 

The specific symptoms of each type of myeloproliferative disorder are: 

• Polycythemia vera: This may cause dizziness, itchiness, enlarged spleen (which appears as a swollen abdomen), bleeding and bruising, blood clots, bone pain, or shortness of breath. It can lead to acute myelogenous leukemia (AML)—a serious type of blood cancer—or myelofibrosis (bone marrow cancer).
• Essential thrombocythemia: Headaches, dizziness, skin rash, numbness, fainting, chest pain, and bleeding are the common symptoms. It can cause serious problems, including stroke (in which blood flow is blocked to part of the brain) and heart attack (in which blood flow is blocked to the heart muscle), and it may rarely progress to myelofibrosis or AML.
• Primary myelofibrosis: Effects can include an enlarged spleen, weight loss, shortness of breath, night sweats, anemia (low red blood cells), bleeding, and blood clots. 
• Chronic myelogenous leukemia: Bleeding, bone pain, weight loss, night sweats, and fevers can occur. This is a type of cancer that can cause other blood cell types to be low, and the myeloid cells may spread throughout the blood.
• Chronic eosinophilic leukemia: It can cause itching, cough, muscle pain, or diarrhea. This condition may progress to AML.
• Chronic neutrophilic leukemia: Liver and spleen enlargement, weight loss, fevers, sore throat, bruising, and bone pain can occur. The condition is slowly progressive and may progress to AML.

You can also be susceptible to getting infections or anemia (low red blood cells), as well as other symptoms with myeloproliferative disorders. 

Causes 

All of the myeloproliferative disorders are caused by a dysfunction of blood cell production in the bone marrow. Red blood cells, white blood cells, and platelets all develop from the same immature bone marrow cells, which are called granulocyte or myeloid precursors. These differentiate (specialize) into certain cell types as they mature. 

These conditions are associated with noninheritable genetic abnormalities that affect blood cell production. The genetic changes may occur due to environmental influences, but they generally have no specific identifiable cause. Myeloproliferative disorders can also develop without the presence of any specific genetic abnormality. 

Smoking is associated with a higher-than-average risk of developing a myeloproliferative disorder, and obesity is associated with a slightly increased risk, but these conditions can develop without any risk factors. The risk of polycythemia vera is also increased with heart disease or underlying cancer. 

Diagnosis

Sometimes myeloproliferative disorders are diagnosed due to an abnormal number of blood cells noted on a blood test done for another reason. These conditions may also be diagnosed during a symptom evaluation.

Tests that are used to diagnose myeloproliferative disorders include: 

• Complete blood count (CBC): This blood test detects the number of blood cells including platelets, red blood cells, and different types of white blood cells. This test is usually part of a routine medical checkup, and it is also often done to evaluate symptoms such as fatigue and feeling sick.
• Blood smear: A blood sample can be examined microscopically to identify specific blood cell changes. 
• Bone marrow aspiration or biopsy: A bone marrow aspiration is a sample of bone marrow tissue that is obtained with a needle and examined microscopically. A bone marrow biopsy is a similar procedure that involves a larger sample. They are both safe procedures and can be uncomfortable, but the discomfort resolves quickly after the procedure. 
• Genetic test: A genetic test can identify mutations that are associated with specific myeloproliferative disorders. 
• Imaging tests: Tests such as X-rays and computed tomography (CT) scans can sometimes detect signs of bone marrow abnormalities. These tests are not typically part of the diagnosis of myeloproliferative disorders, but they can be helpful during the diagnostic process or when complications occur.

The results of these tests differ, depending on which type of myeloproliferative disorder you have. With polycythemia vera, a CBC would show an increased hematocrit, which is a measure of red blood cells. With essential thrombocythemia, a CBC would show a high platelet count, and a blood smear may show clumps of platelets.

Myelofibrosis may be diagnosed with a bone marrow biopsy. Chronic myeloid leukemia, chronic eosinophilic leukemia, and chronic neutrophilic leukemia can show abnormal numbers of specific white blood cells on a bone marrow aspiration or biopsy.

Treatment 

If you have a myeloproliferative disorder, it's important to get treatment to manage your symptoms and prevent your condition from progressing.

Chemotherapy can prevent excess cell production, and the medications are sometimes used to treat myeloproliferative disorders. Each disorder is treated with different chemotherapy, as well as specific medication or other therapy to manage the complications.

For example, hydroxyurea is sometimes used to treat polycythemia vera or essential thrombocytopenia. Interferons, which are immunosuppressants affect the immune system, are sometimes used to treat the different types of chronic leukemia and other myeloproliferative disorders.

Jakafi (ruxolitinib), a tyrosine kinase inhibitor, is used to treat polycythemia vera and myelofibrosis. Polycythemia vera can also be treated with medication to reduce the number of red blood cells, and sometimes removal of blood (therapeutic phlebotomy) is necessary.

Vonjo (pacritinib) is a multikinase inhibitor used to treat people with a rare form of a bone marrow disorder known as intermediate- or high-risk primary or secondary myelofibrosis. Vonjo has the distinction of being the first approved therapy to specifically address the needs of people with cytopenic myelofibrosis (people with a platelet count below 50 x 109/L).

Myelofibrosis and chronic myeloid leukemia are sometimes treated with a bone marrow transplant.

Coping 

If you have a myeloproliferative disorder, you may need lifelong medical care. This can involve surveillance of your symptoms, diagnostic tests, and possibly treatment.

You may need to be cautious about protecting yourself from infections and injuries. This can involve lifestyle adjustments, such as staying away from anyone you know is sick or avoiding activities such as contact sports.

These conditions can be slowly progressive, and they may sometimes increase your risk of cancer. If you need treatment for your myeloproliferative disorder, you might also have side effects of chemotherapy. These side effects should resolve after your treatment course is complete.

Summary

Myeloproliferative disorders cause excess production of red or white blood cells or platelets. They are chronic and slowly get worse over time.

The different types of myeloproliferative disorders depend on which cells are overproduced. These conditions include chronic myelogenous leukemia, polycythemia vera, primary myelofibrosis, essential thrombocythemia, chronic neutrophilic leukemia, and chronic eosinophilic leukemia.

Symptoms vary, but often they are nonspecific and the condition is sometimes caught during a routine blood test, such as a CBC. A bone marrow biopsy is usually needed to diagnose these conditions. Treatment varies depending on the type of disorder, and may include chemotherapy.

A Word From Verywell

Myeloproliferative disorders can be life-changing for you and your loved ones. All of these conditions are rare, and the details of the blood cell overgrowth are often confusing.

Living with a myeloproliferative disorder means taking care of yourself, eating right, staying active, getting enough rest, and giving yourself time to do the things you love and spend time with people you enjoy.