Polycythemia

Book
In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan.
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Excerpt

Polycythemia, or erythrocytosis, refers to an increase in the absolute red blood cell (RBC) mass in the body. In practice, this is reflected by an increase in hemoglobin levels, or hematocrit, over what is considered physiologic for the particular age and gender.

The standard RBC mass does not usually exceed 36 ml/kg in males and 32 ml/kg in females. The reference ranges for normal hemoglobin levels and hematocrit vary depending on altitude, ethnicity, and country. However, as a frame of reference, the hemoglobin and hematocrit of a healthy adult male are 16 g/dL +/- 2 gm/dl and 47% +/- 6%, respectively. The hemoglobin and hematocrit of a menstruating adult female are usually 13 g/dL +/- 2 gm/dl and 40% +/- 6%, respectively. Polycythemia in newborns is defined as a central venous hematocrit over 65% or a hemoglobin value above 22 g/dL.

Polycythemia vera is a sub-type of polycythemia. Often referred to colloquially as simply “polycythemia,” it is an acquired, Philadelphia-chromosome negative, myeloproliferative disorder. This condition can be associated with the overproduction of all three cell lines but with a notable predilection towards red blood cells.

The clinical significance of erythrocytosis, due to any cause, lies in the associated risk of thrombotic events due to hyperviscosity of blood. Additionally, the potential for progression to leukemia in cases of polycythemia vera also warrants additional management strategies to be implemented.

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