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What is the difference between ERYTHROCYTOSIS and POLYCYTHEMIA?
Although the terms are often used interchangeably, they have slightly different meanings.
What is the difference between ERYTHROCYTOSIS and POLYCYTHEMIA?
Although the terms are often used interchangeably, they have slightly different meanings.
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1. ERYTHROCYTOSIS = elevated RBC count.
1a. Absolute erythrocytosis is associated with an absolute increase in RBC count.
1b. Relative erythrocytosis is associated with an apparent increase in RBC count owing to a reduction in plasma volume.
1. ERYTHROCYTOSIS = elevated RBC count.
1a. Absolute erythrocytosis is associated with an absolute increase in RBC count.
1b. Relative erythrocytosis is associated with an apparent increase in RBC count owing to a reduction in plasma volume.
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Absolute erythrocytosis with a normal MCV is associated with elevated red cell mass (polycythemia).
Absolute erythrocytosis with microcytosis (as occurs in thalassemia) may be associated with normal or
even low red cell mass (Hct=MVC x RBC count).
Absolute erythrocytosis with a normal MCV is associated with elevated red cell mass (polycythemia).
Absolute erythrocytosis with microcytosis (as occurs in thalassemia) may be associated with normal or
even low red cell mass (Hct=MVC x RBC count).
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2. POLYCYTHEMIA = elevated Hct and/or Hb.
2a. Absolute polycythemia is associated with an absolute increase in red cell mass, as measured by the RBC mass surrogates Hct and/or Hb.
2b. Relative polycythemia is an elevated Hb or Hct secondary to reduction in plasma volume.
2. POLYCYTHEMIA = elevated Hct and/or Hb.
2a. Absolute polycythemia is associated with an absolute increase in red cell mass, as measured by the RBC mass surrogates Hct and/or Hb.
2b. Relative polycythemia is an elevated Hb or Hct secondary to reduction in plasma volume.
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Absolute polycythemia is usually but not always associated with an absolute increase in RBC count (erythrocytosis) (see graphic).
As the name ‘poly’ implies, polycythemia more accurately refers to pan-myeloproliferation, but this definition is not normally adhered to.
Absolute polycythemia is usually but not always associated with an absolute increase in RBC count (erythrocytosis) (see graphic).
As the name ‘poly’ implies, polycythemia more accurately refers to pan-myeloproliferation, but this definition is not normally adhered to.
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