Polycythemia vera, a chronic blood cancer, is characterized by an overproduction of red blood cells in the bone marrow, classified as a myeloproliferative neoplasm (MPN). While treatment can reduce red blood cell counts, managing the condition’s daily impact may necessitate alternative strategies.
Why Symptoms Persist Despite Normal Blood Counts
“One of our main goals in PV is to maintain a hematocrit level below 45% to reduce the risk of blood clots,” said Neil Dunavin, MD, MS, a hematologist-oncologist at City of Hope Cancer Center Chicago. Hematocrit is the percentage of your blood made up of red blood cells.
However, controlling blood counts and symptoms often do not align, he noted. Even with reassuring lab results, some individuals with PV still experience symptoms or side effects from their treatment.
Fatigue, for example, can have multiple potential causes. “It may come from ongoing PV-associated inflammation, iron deficiency caused or worsened by phlebotomy, or unrelated causes such as poor sleep or thyroid disease,” Dr. Dunavin said.
Adeel Khan, MD, MPH, MS, a hematologist-oncologist and epidemiologist at UT Southwestern Medical Center in Dallas, Texas, said many people with PV begin treatment with therapeutic phlebotomy to keep their hematocrit below 45%, along with low-dose aspirin – typically 81 mg daily – when there are no contraindications.
Therapeutic phlebotomy involves removing a specific volume of blood to reduce red blood cell count. Yet, even when blood counts are controlled, this method may not alleviate all PV symptoms and can also lead to side effects.
According to Dr. Khan, some individuals may continue to face issues such as fatigue, severe itching after contact with water (aquagenic pruritus), headaches, dizziness, burning pain and redness in the hands and feet (erythromelalgia), and an enlarged spleen (splenomegaly).
Managing Itching After Water Exposure
Aquagenic pruritus is a strong itching sensation that can happen when the skin is exposed to water, especially warm water.
“While the precise mechanism is not known, it appears that abnormal JAK2 signaling can make mast cells and basophils in the skin more reactive,” Dr. Dunavin said. “Warm water exposure to the skin can trigger the release of histamine and other itch-causing substances. There usually is no skin rash.”
JAK2 is a gene that’s mutated in most people with PV. Mast cells and basophils are immune cells that store histamine, a chemical involved in the body’s inflammatory and allergic responses.
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Managing itching may be possible through shorter baths or showers, cooler water, applying moisturizer while the skin is damp, and considering antihistamines. Other options include anti-itch creams and phototherapy. Treating the underlying disease can also help.
Because PV increases your risk of blood clots, you should be particularly cautious during long periods of sitting, whether traveling or working.
Dr. Khan emphasized that, ideally, your PV should be well managed before traveling. This includes maintaining a hematocrit below 45%, taking aspirin as prescribed, addressing cardiovascular risk factors, avoiding recent uncontrolled bleeding, and, most importantly, having no recent thrombosis (blood clots).
If you’re going to be sitting for an extended period, he recommends avoiding long periods without movement, standing, walking, stretching, or doing calf exercises regularly, staying hydrated, and asking your care team whether graduated compression stockings may help.
He also recommends taking extra precautions when traveling at high altitudes because lower oxygen levels may increase the risk of blood clots.
It may be helpful to keep a record of your symptoms between doctor’s visits so you can share them with your provider.
He recommends tracking symptoms such as fatigue, itching after water exposure, headaches, vision changes, dizziness, burning or redness in the hands or feet, bone pain, night sweats or fever, abdominal fullness or feeling full sooner than usual, and difficulty concentrating.
When Treatment Plans Need Adjustment
According to Dr. Khan, your treatment should be reassessed if your symptoms worsen or interfere with your daily life, your hematocrit does not remain within your target range, phlebotomies become frequent or difficult to tolerate, your white blood cell or platelet counts continue to rise, your spleen becomes enlarged, or you experience unusual bleeding or a blood clot.
If any of these occur, phlebotomy and aspirin may no longer be enough to control your PV. Dr. Khan said your care team may need to consider cytoreductive or symptom-focused treatment, including medications like hydroxyurea.