Polycythemia Vera

Polycythemia (say: "polly-sigh-thee-me-ah") vera (PV), is also known as primary polycythemia, erythremia, polycythemia rubra vera, splenomegalic polycythemia, or Vaquez-Osler disease is a chronic myeloproliferative disorder characterized by increased red blood cell (RBC) mass, leukocytosis, thrombocytosis, and increased hemoglobin concentration, with normal or increased plasma volume. It usually occurs between the ages of 40 and 60, most commonly among males of Jewish ancestry; it rarely affects children or blacks and doesn't appear to be familial.

The prognosis depends on age at diagnosis, the treatment used, and complications. Mortality is high if polycythemia is untreated or is associated with leukemia or myeloid metaplasia.

Causes

In polycythemia vera, uncontrolled and rapid cellular reproduction and maturation cause proliferation or hyperplasia of all bone marrow cells (panmyelosis). The cause of such uncontrolled cellular activity is unknown, but it is probably due to a multipotential stem cell defect.

Signs and symptoms

When there is an increase blood volume and viscosity (thickness), complications associated with this disease can occur. The following are the most common symptoms of polycythemia vera. However, each individual may experience symptoms differently. Symptoms may include:

• fatigue
• headache
• dizziness
• shortness of breath
• visual disturbances
• inability to concentrate
• night sweats
• flushed complexion
• nosebleeds
• bleeding gums
• excessive menstrual bleeding
• hemoptysis (coughing up blood)
• bruising
• itchy skin (particularly after a hot bath)
• gout
• numbness
• high blood pressure (hypertension)

Arterial or venous thrombosis can occur, resulting in a heart attack, stroke, or pulmonary embolism. The symptoms of polycythemia vera may resemble other blood disorders or medical problems. Always consult your physician for a diagnosis.

Diagnosis

Laboratory studies confirm polycythemia vera by showing increased RBC mass and normal arterial oxygen saturation in association with splenomegaly or two of the following: thrombocytosis, leukocytosis, elevated leukocyte alkaline phosphatase level, or elevated serum vitamin B12 or unbound B12 -binding capacity.

Another common finding is increased uric acid production, leading to hyperuricemia and hyperuricuria. Other laboratory results include increased blood histamine, decreased serum iron concentration, and decreased or absent urinary erythropoietin. Bone marrow biopsy reveals panmyelosis.

Treatment

Phlebotomy can reduce RBC mass promptly. The frequency of phlebotomy and the amount of blood removed each time depend on the patient's condition. Typically, 350 to 500 ml of blood can be removed every other day until the hematocrit is reduced to the lownormal range.

After repeated phlebotomies, the patient develops iron deficiency, which stabilizes RBC production and reduces the need for phlebotomy. Pheresis permits the return of plasma to the patient, diluting the blood and reducing hypovolemic symptoms.

Phlebotomy doesn't reduce the white blood cell or platelet count and won't control the hyperuricemia associated with marrow cell proliferation.

For severe symptoms, myelosuppressive therapy may be used. In the past, radioactive phosphorus (3zP) or chemotherapeutic agents, such as melphalan, busulfan, or chlorambucil, could usually control the disease. However, these agents may cause leukemia and should be reserved for older patients and those with problems uncontrolled by phlebotomy.

The current preferred myelosuppressive agent is hydroxyurea, which isn't associated with leukemia. Patients who have had previous thrombotic problems should be considered for myelosuppressive therapy.