Myeloproliferative neoplasms (MPNs), also called myeloproliferative disorders, can lead to many health changes. People with MPNs often experience weakness that makes it hard to keep up with everyday life. Physical weakness, also called asthenia, often appears with related symptoms like tiredness, dizziness, lightheadedness, or ataxia (loss of coordination).

Members of myMPNteam say that weakness has been a problem when living with MPNs. “I hung up my laundry and my knees were shaking bad. … Is weakness a symptom?” asked one member. Another member answered, “My extremities do feel weak at times. Typically my arms and hands. I’ll start dropping things.” “I had a very active week and felt like rubbish for the weekend,” wrote one member. “Weakness in my legs, extreme fatigue, and digestive issues.”

What Causes Weakness In People With MPNs?

For many people, weakness is one of the ongoing symptoms of MPNs. This disease causes blood cell problems and a decrease in red blood cells, leading to weakness and other symptoms. In some cases, weakness can also be a side effect of MPN treatment.

How Do MPNs Cause Weakness?

MPNs begin in the bone marrow — the soft, spongy tissue found inside of certain bones. Within the bone marrow are many stem cells and early cell precursors that make all of the different types of blood cells. With MPNs, these cells become damaged, leading to changes in genes like JAK2, MPL, and CALR. The abnormal stem cells begin making too many white blood cells, red blood cells, or platelets. When the body makes too many of one type of blood cell, levels of other blood cells may decrease.

Weakness during MPNs is often linked to anemia (low levels of red blood cells). Red blood cells are responsible for bringing oxygen to all of the body’s tissues and carrying away carbon dioxide waste. A person develops anemia when there aren’t enough healthy red blood cells, or when iron levels get too low. This condition may also develop as a result of ongoing inflammation.

Anemia leads to symptoms like:

• Weakness
• Fatigue
• Shortness of breath
• Dizziness
• Headache
• Rapid heart rate
• Feeling cold when everyone around you feels fine
• Pale or dry skin
• Easy bruising

Anemia can develop in two of the three main types of MPNs: primary myelofibrosis (PMF) or essential thrombocythemia. Polycythemia vera is an MPN in which there are actually too many red blood cells, rather than too few. However, nearly everyone diagnosed with PV develops an iron deficiency. Even though PV doesn’t generally cause anemia, it can still lead to feelings of weakness. In addition, in late stages of myelofibrosis, there may be scarring of the bone marrow, leaving less space to produce blood cells, and leading to anemia

Some myMPNteam members have reported that anemia can be a tough condition to deal with. One member said, “The anemia is exhausting me.” Another explained, “Anemia is really hard on the body. You get so fatigued when you have iron-poor blood.”

Weakness as a Treatment Side Effect

Chemotherapy drugs are sometimes used to treat MPNs. These medications can kill abnormal blood cells and reduce blood cell counts when they are too high. However, chemotherapy drugs can also lead to side effects, including weakness, fatigue, trouble focusing, and anemia.

Jakavi (ruxolitinib) is a common MPN treatment. It targets one of the gene changes that causes MPNs, and forces stem cells to stop producing so many blood cells. As many as 1 out of 5 people who take ruxolitinib experience side effects. One common side effect is anemia, so people who use this drug may experience weakness as a result. Inrebic (fedratinib), a similar drug, was approved in 2019 by the U.S. Food and Drug Administration (FDA).

Interferon drugs are a type of immunotherapy that work with the body’s immune system to get rid of extra blood cells. They include drugs like Intron A (interferon alfa-2b) and Pegasys (peginterferon alfa-2a). Unfortunately, interferon drugs come with sometimes severe side effects, including infections and depression. These drugs are now less commonly used.

Some people with PMF may undergo radiation therapy in order to treat symptoms like splenomegaly (an enlarged spleen). Radiation treatments may lead to tiredness and weakness.

Other Factors That May Lead to Weakness

MPN or its treatments may also be linked to several other factors or conditions that can cause weakness. Some of these include:

• Not eating a balanced diet
• Having certain vitamin deficiencies
• Not drinking enough water
• Getting insufficient physical activity throughout the day
• Spending more time sitting or laying down, which can lead to weaker muscles
• Trying to do more physically than the body can handle
• Not getting enough good quality sleep
• Dealing with a lot of untreated pain
• Feeling stressed, anxious, or depressed
• Having other underlying health conditions, such as thyroid gland disorders

Managing Weakness While Living With an MPN

If you realize that you are feeling weaker than normal, a good first step is talking to your health care team. Some weakness is expected when living with an MPN. However, weakness can sometimes be an indication that something else is going on or that you need to change your treatment plan.

Treating Anemia

Getting your anemia under control may go a long way in treating weakness. Some medications can help treat anemia for people with MPNs, such as:

• Corticosteroids
• Hormone medications like Danocrine (danazol) or Halotestin (fluoxymesterone)
• Epogen (epoetin alfa) or other erythropoiesis-stimulating agents
• Revlimid (lenalidomide)
• Thalomid (thalidomide)

MPN-related anemia is also treated with blood transfusions. During this process, you receive new blood cells from a donor. The transfusion is given through an IV line in which a small tube delivers blood cells directly into the veins.

Lifestyle Changes

If you are experiencing muscle weakness, you may have trouble getting around. You may also be at risk of injury from falls. You may need to change your daily routine in order to help keep yourself safe.

Get in the habit of walking more slowly in order to make sure that your muscles can keep up. Ask a loved one for help moving around if your weakness is severe.

You can reduce your risk of falls by wearing comfortable shoes that fit you well. Additionally, keep walkways in your living space clear of objects and rugs. Use bright light to make sure you can see your path well enough to prevent tripping or falling.

Physical Therapy and Occupational Therapy

Physical therapists can help you build up strength, move around more easily, and prevent injuries. Occupational therapists, on the other hand, focus on helping you complete daily tasks. If an activity becomes too difficult because of muscle weakness, an occupational therapist may be able to help you learn a new way of performing it. Both of these types of therapy may be helpful for people experiencing weakness.

Trying a New Treatment Plan

If side effects from one therapy are too much to handle, you may be able to try a different treatment option. Some myMPNteam members have experienced improved quality of life after changing medications.

“I had all kinds of pain and weakness on Droxia (hydroxyurea),” wrote one member. This member was able to gain back some muscle strength when they switched to ruxolitinib. Another member also reported a negative experience with this medication. “Hydroxyurea wreaked havoc on my bloodwork and wasn’t the right drug for me,” they said. “It caused me to be anemic, resulting in two blood transfusions.”

If you are struggling with this side effect, ask your doctor or pharmacist whether weakness may be caused by your current treatment plan. However, never stop taking any treatments without first talking to your doctor.

Talk With Others Who Understand

On myMPNteam, the social network for people living with myeloproliferative neoplasms and their loved ones, members come together to ask questions, give advice, and share their stories with others who understand life with MPNs.

Have you been experiencing weakness while living with an MPN? Share your experience in the comments below, or start a conversation by posting on myMPNteam.