Polycythemia is a neoplasm in which the bone marrow makes too many red blood cells. It may also result in the overproduction of white blood cells and platelets.
Most of the health concerns associated with polycythemia vera are caused by the blood being thicker as a result of the increased red blood cells. It is more common in the elderly and may be symptomatic or asymptomatic. Common signs and symptoms include itching (pruritus), and severe burning pain in the hands or feet that is usually accompanied by a reddish or bluish coloration of the skin. Patients with polycythemia vera are more likely to have gouty arthritis. Treatment consists primarily of phlebotomy.
For many people, polycythemia vera may not cause any signs or symptoms. However, some people may experience:
- Itchiness, especially following a warm bath or shower
- Excessive sweating
- Painful swelling of one joint, often the big toe
- Shortness of breath
- Breathing difficulty when you lie down
- Numbness, tingling, burning or weakness in your hands, feet, arms or legs
- A feeling of fullness or bloating in your left upper abdomen due to an enlarged spleen
Because polycythemia vera causes your blood to thicken and slows blood flow, it increases your risk of developing blood clots. If a blood clot occurs in your head, it can cause a stroke. Seek emergency medical care if you have any of the following signs or symptoms of a stroke:
- Sudden numbness, weakness, or paralysis of your face, arm or leg — usually on one side of your body
- Sudden difficulty speaking or understanding speech (aphasia)
- Sudden blurred, double or decreased vision
- Sudden dizziness, loss of balance or loss of coordination
- A sudden, severe headache or an unusual headache, which may or may not be accompanied by a stiff neck, facial pain, pain between your eyes, vomiting or altered consciousness
- Confusion, or problems with memory, spatial orientation or perception
Polycythemia vera occurs when a mutation in a bone marrow cell causes a problem with blood cell production. Normally, your body carefully regulates the number of each of the three types of blood cells you have. But in polycythemia vera, the mechanism your body uses to control the production of blood cells becomes damaged, and your bone marrow makes too many of some blood cells.
The mutation that causes polycythemia vera is thought to affect a protein switch that tells the cells to grow. Specifically, it's a mutation in the protein JAK2 (the JAK2 V617F mutation). Most people with polycythemia vera have this mutation. There are other mutations found in people with polycythemia vera, but it's not yet known what role these mutations play in the development of the disease or what the implications of these mutations might mean for treating the disease.
It's not clear what causes the mutations seen in polycythemia vera. Researchers believe the mutation occurs after conception — meaning that your mother and father don't have it — so it's acquired, rather than inherited from a parent.
The risk of polycythemia vera increases with age. It is more common in adults older than 60, though the disease can occur at any age.
- An increase in the number of red blood cells and, in some cases, an increase in platelets or white blood cells.
- Elevated hematocrit measurement, the percentage of red blood cells that make up total blood volume.
- Elevated levels of hemoglobin, the iron-rich protein in red blood cells that carries oxygen.
- Very low levels of erythropoietin, a hormone that stimulates bone marrow to produce new red blood cells.
If an examination of your bone marrow shows that it's producing higher than normal numbers of blood cells, it may be a sign of polycythemia vera.
Tests for gene mutation
If you have polycythemia vera, analysis of your bone marrow or blood also may show the mutation in the cells (JAK2 V617F mutation) that's associated with the disease.
Possible complications, if not treated, of polycythemia vera include:
- Blood clots: Polycythemia vera causes your blood to be thicker than normal, which can slow the rate of blood flow through your veins and arteries. Increased blood thickness and decreased blood flow, as well as abnormalities in your platelets, increase your risk of blood clots. Blood clots can cause a stroke, a heart attack, or blockage of an artery in your lungs (pulmonary embolism) or in a vein deep within a muscle (deep vein thrombosis).
- Enlarged spleen (splenomegaly): Your spleen helps your body fight infection and filter unwanted material, such as old or damaged blood cells. The increased number of blood cells caused by polycythemia vera makes your spleen work harder than normal, which causes it to enlarge.
- Skin problems: Polycythemia vera may cause your skin to itch, especially after a warm bath or shower, or after sleeping in a warm bed. You may experience a burning or tingling sensation in your skin, particularly on your arms, legs, hands or feet. Your skin may also appear red, especially on your face.
- Problems due to high levels of red blood cells: Too many red blood cells can lead to a number of other complications, including open sores on the inside lining of your stomach, upper small intestine or esophagus (peptic ulcers) and inflammation in your joints (gout).
- Other blood disorders: In rare cases, polycythemia vera may lead to other blood diseases, including a progressive disorder in which bone marrow is replaced with scar tissue (myelofibrosis), a condition in which stem cells don't mature or function properly (myelodysplastic syndrome), or cancer of the blood and bone marrow (acute leukemia).
Polycythemia vera is a chronic condition that can't be cured. Treatment focuses on reducing the amount of blood cells. In many cases, treatment can prevent complications from polycythemia vera and decrease or eliminate the disease's signs and symptoms.
Treatment may include:
- Taking blood out of your veins: Drawing a certain amount of blood out of your veins in a procedure called phlebotomy is usually the first treatment option for people with polycythemia vera. This reduces the number of blood cells and decreases your blood volume, making it easier for your blood to function properly. How often you need phlebotomy depends on the severity of your condition.
- Low-dose aspirin: Your doctor may recommend that you take a low dose of aspirin to reduce your risk of blood clots. Low-dose aspirin may also help reduce burning pain in your feet or hands.
- Medication to decrease blood cells: For people with polycythemia vera who aren't helped by phlebotomy alone, medications, such as hydroxyurea (Droxia, Hydrea), to suppress your bone marrow's ability to produce blood cells may be used. Interferon alpha may be used to stimulate your immune system to fight the overproduction of red blood cells.
- Therapy to reduce itching: If you have bothersome itching, your doctor may prescribe medication, such as antihistamines, or recommend ultraviolet light treatment to relieve your discomfort. Medications that are normally used to treat depression, called selective serotonin reuptake inhibitors (SSRIs), may be helpful in relieving itching. Examples of SSRIs include paroxetine (Paxil) or fluoxetine (Prozac)
- Approved therapy: Ruxolitinib (Jakafi) FDA approved "Treatment of patients with polycythemia vera who have had an inadequate response to or are intolerant of hydroxyurea".