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What Is the Differe...

Metadata

• Author: @WilliamAird4 on Twitter
• Full Title: 1/5
  What Is the Differe...
• Category: #tweets
• URL: https://twitter.com/WilliamAird4/status/1622951856577323009

Highlights

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  What is the difference between ERYTHROCYTOSIS and POLYCYTHEMIA?
  Although the terms are often used interchangeably, they have slightly different meanings.
  (View Tweet)
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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. (View Tweet)
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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). (View Tweet)
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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. (View Tweet)
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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. (View Tweet)