– An increase in the number of circulating erythrocytes and in the hemoglobin concentration that is manifested in three forms: polycythemia vera, secondary polycythemia, and relative polycythemia.
Causes and Incidence
The cause of polycythemia vera is unknown, and the disorder is usually seen in older Jewish men. It occurs in 1 in 200,000 people in the United States. Secondary polycythemia is a compensatory response to tissue hypoxia associated with underlying chronic obstructive pulmonary disease; hemoglobin abnormalities such as carboxyhemoglobinemia, which is seen in heavy smokers; congestive heart failure; congenital heart disease; or prolonged exposure to altitudes above 10,000 feet. The incidence is about 2 in 100,000 people in the United States. Relative polycythemia is caused by fluid loss and dehydration and disappears when fluids are replaced.
Polycythemia vera involves rapid, uncontrolled cellular reproduction and maturation, which causes hyperplasia of all bone marrow cells and replaces bone marrow fat. Increased megakaryocytes may be present and form clumping patterns. Bone marrow iron is absent in about 90% of affected individuals. The cellular overproduction increases blood viscosity and blood volume, and organs and tissues become engorged with blood.
Weakness and fatigue; a feeling of fullness in the head, with headache, lightheadedness, and dizziness; visual disturbances (scotoma, double or blurred vision); dyspnea; nosebleeds; night sweats; and epigastric and joint pain; later signs include pruritus, clubbing of digits, a reddened face with engorged retinal veins, and hepatosplenomegaly
Above manifestations plus hypoxemia in the absence of hepatosplenomegaly and hypertension
Often individual has no complaints or vague complaints (e.g., headache, fatigue) with ruddy complexion and slight hypertension when recumbent
Thrombosis, cerebrovascular accident, peptic ulcers, myeloid metaplasia, leukemia, and hemorrhage are common complications in polycythemia vera and result in the death of about 50% of untreated individuals within 18 months of the appearance of symptoms. The median survival rate in treated individuals is 7 to 15 years.Hemorrhage is the most common complication of secondary polycythemia. Hypercholesterolemia, hyperlipidemia, and hyperuricemia may complicate relative polycythemia.
Increased RBC mass and normal arterial oxygen saturation associated with splenomegaly or two of the following: thrombocytosis, leukocytosis, elevated leukocyte alkaline phosphatase, elevated serum B12; bone marrow reveals panmyelosis
Elevated erythrocytes, hematocrit, hemoglobin, mean corpuscular volume; absence of leukocytosis and thrombocytosis; erythroid hyperplasia of bone marrow
Normal or decreased RBC mass; elevated hematocrit; no leukocytosis; normal plasma volume; normal bone marrow studies
Splenectomy to treat resistant splenomegaly.
Chemotherapeutic agents to induce myelosuppression in some polycythemia vera cases; allopurinol to treat hyperuricemia; antihistamines for pruritus; analgesics for joint pain.
Polycythemia vera: phlebotomy to reduce RBC mass; pheresis for removal of WBCs, RBCs, and platelets; exercise to promote circulation; monitoring for thrombus formation, hemorrhage, and ulcer formation Secondary polycythemia: treatment of underlying causes Relative polycythemia: fluid and electrolyte replacement, measures to prevent further fluid loss.