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an increase in the total red blood cell mass of the blood; called also erythrocythemia, hypercythemia, and hypererythrocythemia.

There are two distinct forms of the disease: Primary polycythemia (polycythemia vera) is a myeloproliferative disorder of unknown etiology. It is characterized by hyperplasia of the cell-forming tissues of the bone marrow, with resultant elevation of the erythrocyte count and hemoglobin level, and an increase in the number of leukocytes and platelets.

Secondary polycythemia is a physiologic condition resulting from a deficient oxygen supply to the tissues. The body attempts to compensate for the deficiency by manufacturing more hemoglobin and erythrocytes. Living at high altitudes can produce polycythemia, as can severe chronic lung and heart disorders, especially congenital heart defects.

Absolute polycythemia refers to an increase in red cell mass from any cause. Relative polycythemia refers to a loss of plasma volume causing an elevated hematocrit.
Symptoms. The symptoms of primary and secondary polycythemia are much the same. The increased erythrocyte production results in thickening of the blood and an increased tendency toward clotting. The viscosity of the blood limits its ability to flow properly, so that the supply to the brain and other vital tissues is diminished. This may cause sluggishness, irritability, headache, dizziness, fainting, disturbances of sensation in the hands and feet, and a feeling of fullness in the head. There may be episodes of acute pain as spontaneous clots occur in the blood vessels. The spleen becomes enlarged and the smaller veins become more prominent, so that the skin has a bluish hue. The secondary form is often accompanied by enlargement of the tips of the fingers (clubbing).
Treatment. Treatment of polycythemia vera is aimed at reducing the red cell count and decreasing the blood volume. Mild cases can be managed by periodic phlebotomy. More serious cases may require myelosuppressive therapy; interferon and large-dose aspirin therapy may also be used. Research on treatment modalities is ongoing. In secondary polycythemia, successful treatment of the causative illness will relieve the polycythemia.


The presence of an abnormally high number of red blood cells in the circulating blood.
See also: polycythemia.
[hyper- + G. kytos, cell, + haima, blood]


/poly·cy·the·mia/ (-si-thēm´e-ah) an increase in the total cell mass of the blood.
absolute polycythemia  an increase in red cell mass caused by increased erythropoiesis, which may occur as a compensatory physiologic response to tissue hypoxia or as the principal manifestation of polycythemia vera.
hypertonic polycythemia  stress p.
relative polycythemia  a decrease in plasma volume without change in red blood cell mass so that the erythrocytes become more concentrated (elevated hematocrit), which may be an acute transient or a chronic condition.
polycythemia ru´bra  p. vera.
secondary polycythemia  any absolute increase in the total red cell mass other than polycythemia vera, occurring as a physiologic response to tissue hypoxia.
stress polycythemia  chronic relative polycythemia usually affecting white, middle-aged, mildly obese males who are active, anxiety-prone, and hypertensive.
polycythemia ve´ra  a myeloproliferative disorder of unknown etiology, characterized by abnormal proliferation of all hematopoietic bone marrow elements and an absolute increase in red cell mass and total blood volume, associated frequently with splenomegaly, leukocytosis, and thrombocythemia.


A condition characterized by an abnormally high number of red blood cells in the blood.


A condition marked by an abnormally large number of red blood cells in the circulatory system.


Etymology: Gk, polys + kytos, cell, haima, blood
an increase in the red blood cell count and circulating red blood cell mass that may be primary or secondary to pulmonary disease, heart disease, or prolonged exposure to high altitudes. Also called Osler's disease, polycythemia vera. Compare hypoplastic anemia, leukemia. See also altitude sickness, erythrocytosis.
observations Clinical manifestations for polycythemia include weakness and fatigue; headache and vertigo; 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. Secondary polycythemia may display hypoxemia in the absence of hepatosplenomegaly and hypertension. Lab results in primary polycythemia include elevated red blood cell counts; elevated white blood cell counts with basophilia; elevated hemoglobin; thrombocytosis; elevated alkaline phosphatase, uric acid, and albumin, and elevated histamine levels with low serum erythropoietin levels. Bone marrow aspiration shows panmyelosis. Thrombosis, cerebrovascular accident, peptic ulcers, myeloid metaplasia, leukemia, and hemorrhage are common complications in primary polycythemia 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.
interventions Management of secondary polycythemia is directed at treating the underlying causes. The treatment for primary polycythemia is directed at reducing blood volume and viscosity and inhibiting bone marrow activity. The treatment mainstay is serial phlebotomy and is used to reduce RBC mass. Hydration therapy is used to reduce blood viscosity. Chemotherapeutic agents may be used to induce myelosuppression. Adjunctive therapy includes allopurinol to treat hyperuricemia, antihistamines to reduce pruritus, analgesics for joint pain, and antacids for gastric hyperacidity. A splenectomy may be indicated to treat resistant splenomegaly.
nursing considerations Nursing during the acute phase includes careful monitoring of intake and output during hydration therapy and phlebotomy to avoid overhydration or underhydration. Comfort measures are instituted to relieve joint pain, itching, and heartburn. Passive and active range of motion and ambulation are used to promote circulation and prevent thrombus formation. If chemotherapeutic agents are used, education is needed about effects and side effects. Education is also important, and stress is placed on the chronic nature of disease, the need for long-term phlebotomy treatment, and the impending complications that will occur if the disease is left untreated.
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Any ↑ RBC mass. See Relative polycythemia, Secondary polycythemia.
Polycythemia types
Relative RBC mass is above normal but not pathologic. See Relative polycythemia.
Secondary to various physiopathologic mechanisms, usually hypoxia or ↑ erythropoietin secretion
Neoplastic, ie polycythemia vera, see there  . ;.


An abnormal increase in the number of red blood cells.
Synonym(s): erythrocythemia, polycythaemia.
[poly- + G. kytos, cell, + haima, blood]


(pol?e-si-the'me-a) [ poly- + cyto- + -emia]
An excess of red blood cells. In a newborn, it may reflect hemoconcentration due to hypovolemia or prolonged intrauterine hypoxia, or hypervolemia due to intrauterine twin-to-twin transfusion or placental transfusion resulting in delayed clamping of the umbilical cord. Synonym: erythrocytosis

Chuvash polycythemia

An autosomal recessive erythrocytosis in which patients respond to normal oxygen levels as if they were in an hypoxic environment and make more red blood cells than are needed. ASludging of blood, pulmonary hypertension, and vascular infarcts are common sequelae.

relative polycythemia

A relative (rather than an absolute) increase in the number of erythrocytes due to a reduction of plasma volume, e.g., in patients with burns or dehydration.

secondary polycythemia

Polycythemia due to a physiological condition that stimulates erythropoiesis, e.g., lowered oxygen tension in blood.

spurious polycythemia

Gaisböck syndrome.
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POLYCYTHEMIA VERA: peripheral blood smear in polycythemia vera (X 400)
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polycythemia vera

A chronic, life-shortening myeloproliferative disorder due to the reproduction of a single stem-cell clone. It is characterized by proliferation or hyperplasia of all bone marrow cells, with an increase in red blood cell mass and hemoglobin concentration that occurs independently of erythropoietin stimulation. Synonym: erythremiaillustration;


Usually occurring between ages 40 and 60 and most common in males with Jewish ancestry, polycythemia seldom affects children or those of African ancestry. Weakness, fatigue, headache, blood clotting, vertigo, tinnitus, irritability, dyspnea, visual disturbances, flushing of face, redness, or ruddy cyanosis, pruritus, ecchymosis, hypertension, epigastric distress, weight loss, and pain in joints or extremities occur commonly. The bone marrow shows uncontrolled, rapid cellular reproduction and maturation (increased cellularity). Peptic ulcers are often reported.


The mainstay of patient care is the reduction in red blood cell mass with recurrent phlebotomy to lower the hematocrit to 45% or less. Vitals signs are monitored during and after phlebotomy, and the patient is provided with oral fluids and protected from orthostatic hypotension. The symptoms and the need to seek medical attention when signs and symptoms of bleeding and thrombus formation occur are explained to the patient. Rest should be balanced with exercise, but the patient should be advised that activity and ambulation help prevent thrombotic complications. Reassurance and support are provided to the patient and family, and opportunities are provided for questions and discussion of concerns. Patients who have a history of blood clotting or very high platelet counts are treated with myelosuppressive drugs, such as hydroxyurea. During myelosuppressive therapy the patient is informed about adverse effects that may occur, assessed for leukopenia and thrombocytopenia, and protective measures are taught and instituted.



A condition characterized by an overabundance of red blood cells.


An abnormal increase in the number of red blood cells.
Synonym(s): erythrocythemia, polycythaemia.
[poly- + G. kytos, cell, + haima, blood]


an increase in the circulating red blood cell mass.
There are two distinct forms:
Primary polycythemia is a myeloproliferative disorder of unknown etiology. It occurs as an inherited defect in cattle and is a rare disease in dogs and cats. There is hyperplasia of the cell-forming tissues of the bone marrow, with resultant elevation of the erythrocyte count and hemoglobin level, and an increase in the number of leukocytes and platelets. Called also polycythemia vera.
Secondary polycythemia is a physiological condition resulting from a decreased oxygen supply to the tissues, caused by living at high altitudes, heart disease, circulatory insufficiency or severe pulmonary disease, or the production of erythropoietin or erythropoietin-like compounds, as in polycystic kidney disease, hydronephrosis or renal neoplasms.

absolute polycythemia
an increase in total hemoglobin and red cell mass with a normal plasma volume. May be a primary or secondary polycythemia.
compensatory polycythemia
a secondary polycythemia, occurring in response to impairment of oxygenation.
familial polycythemia
occurs as an autosomal recessive trait in Jersey cattle. See primary polycythemia (above).
inherited polycythemia
an inherited defect of cattle. Clinically there is dyspnea.
relative polycythemia
apparent polycythemia resulting from loss of plasma and the hemoconcentration that follows. Called also spurious polycythemia.
polycythemia vera
see primary polycythemia (above).
References in periodicals archive ?
A total of 93 subjects with classical myeloproliferative neoplasms were evaluated in the study, 33(35%) of them were polycythaemia vera, 36 (39%) were essential thrombocythaemia and 24 (26%) were having idiopathic myelofibrosis.
Are current methods of measurement of erythropoietin (EPO) in human plasma or serum adequate for the diagnosis of polycythaemia vera and the assessment of EPO deficiency.
In Arthur's case however the blood test seems to show that he has the condition Polycythaemia Vera, if he has I will tell you about it next week.
Fischer T, Kirkpatrick The Incidence of Myelofibrosis in Essential Thrombocythaemia, Polycythaemia vera and Chronic Idiopathic Myelofibrosis: A Retrospective Evaluation of Sequential Bone Marrow Biopsies.