Published: 18 Jun 2025

ICD9: 238.4      ICD10: D45      ICD11: 2A20.4

Polycythemia Vera (PV) is a rare type of blood cancer in which your bone marrow makes too many red blood cells.
This excess of red blood cells thickens your blood, slowing its flow. This can lead to serious problems such as blood clots, which can cause a stroke or heart attack.

Here's a breakdown of important aspects of PV:

Key Characteristics:

Overproduction of Red Blood Cells: The hallmark of PV is the uncontrolled production of red blood cells in the bone marrow. While white blood cells and platelets can also be elevated, the red blood cell count is the primary driver of the disease.
Thickened Blood (Hyperviscosity): The excessive number of red blood cells thickens the blood, making it harder to flow through blood vessels.
Slowed Blood Flow: Thickened blood doesn't flow as efficiently, increasing the risk of clots.
JAK2 Mutation: Most people with PV have a mutation in the JAK2 gene. This gene provides instructions for making a protein that signals blood cells to grow and divide. The JAK2 mutation causes the bone marrow to overproduce blood cells, even when it's not needed.

Symptoms:

Many people with PV don't experience any noticeable symptoms early on. As the disease progresses, symptoms may include:

Fatigue: Feeling tired and weak.
Itching: Especially after a warm bath or shower (aquagenic pruritus).
Headache: Persistent or frequent headaches.
Dizziness: Feeling lightheaded or unsteady.
Shortness of Breath: Difficulty breathing, especially with exertion.
Blurred Vision or Double Vision: Related to changes in blood flow to the eyes.
Redness of the Skin: Especially on the face, palms, and soles of the feet.
Enlarged Spleen (Splenomegaly): The spleen works harder to filter the excess blood cells.
Bleeding: Easy bruising, nosebleeds, or bleeding gums. This can seem paradoxical, as you might expect thicker blood to clot more easily. However, very high platelet counts or impaired platelet function can paradoxically lead to bleeding.
Blood Clots (Thrombosis): The most serious complication. Clots can form in veins (deep vein thrombosis or DVT), arteries (leading to stroke or heart attack), or less common sites.
Burning sensation in the hands or feet.
Gout: Elevated levels of uric acid in the blood due to increased cell turnover can lead to gout.

Causes:

The exact cause of PV isn't fully understood, but it's generally considered to be a genetic mutation acquired *after* conception (i.e., it's not inherited from parents). The *JAK2* gene mutation is found in over 95% of people with PV. Other gene mutations may also be involved.

Diagnosis:

PV is usually diagnosed through blood tests. Key findings include:

Elevated Red Blood Cell Count (Hematocrit): Hematocrit is the percentage of red blood cells in your blood.
Elevated Hemoglobin Level: Hemoglobin is the protein in red blood cells that carries oxygen.
Elevated White Blood Cell Count and Platelet Count (sometimes): These can also be elevated, but not always.
Low Erythropoietin (EPO) Level: EPO is a hormone that stimulates red blood cell production. In PV, EPO levels are typically low because the bone marrow is already overproducing red blood cells.
JAK2 Mutation Testing: A bone marrow biopsy can confirm the diagnosis and rule out other conditions.

Treatment:

PV is a chronic condition, but treatment can help manage symptoms, reduce the risk of complications, and improve quality of life. Treatment options include:

Phlebotomy: Regular blood removal to reduce the number of red blood cells. This is often the first-line treatment.
Low-Dose Aspirin: To help prevent blood clots.
Cytoreductive Therapy: Medications to suppress the bone marrow's production of blood cells. Common medications include:
Hydroxyurea: A chemotherapy drug that slows cell growth.
Ruxolitinib: A JAK2 inhibitor that targets the underlying genetic mutation. This is often used when hydroxyurea is ineffective or causes intolerable side effects.
Interferon alfa: Can be used to reduce blood cell counts.
Treatment of Complications: Addressing any specific complications, such as blood clots, ulcers, or infections.

Prognosis:

With proper management, people with PV can often live for many years. However, the disease can progress to more serious conditions, such as:

Myelofibrosis: Scarring of the bone marrow.
Acute Leukemia: A type of blood cancer.
Transformation to other Myeloproliferative Neoplasms: Such as Essential Thrombocythemia.

Living with Polycythemia Vera:

Follow your doctor's instructions carefully.
Attend all scheduled appointments and blood tests.
Report any new or worsening symptoms to your doctor promptly.
Stay hydrated. Dehydration can worsen blood viscosity.
Avoid iron supplements, unless specifically directed by your doctor. Iron can stimulate red blood cell production.
Maintain a healthy lifestyle. Including a balanced diet and regular exercise.
Manage stress.
Quit smoking. Smoking increases the risk of blood clots.
Protect yourself from injuries. Due to the increased risk of bleeding and bruising.

In summary, Polycythemia Vera is a blood cancer characterized by the overproduction of red blood cells, leading to thickened blood and an increased risk of complications like blood clots. Diagnosis involves blood tests and genetic testing, and treatment aims to control red blood cell production and prevent complications.

Important Note: This information is for general knowledge and informational purposes only, and does not constitute medical advice. It is essential to consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment. Self-treating can be dangerous.