Acquired Erythrocytosis



Acquired Erythrocytosis


Kathryn Foucar, MD









Peripheral blood smear from a patient with severe chronic hypoxia shows secondary erythrocytosis requiring ongoing phlebotomy. Note closely packed microcytic, hypochromic red blood cells.






Blood smear from a patient with polycythemia vera shows leukocytosis, neutrophilia, and erythrocytosis. Erythrocytes are microcytic/hypochromic, secondary to phlebotomy-associated iron deficiency.


TERMINOLOGY


Synonyms



  • Polycythemia


Definitions



  • Hgb/Hct/RBC count above age-/sex-related normal ranges


  • Erythrocytoses are further subclassified into primary, secondary, and relative erythrocytosis



    • Primary and secondary erythrocytosis show true increase


    • Relative erythrocytosis



      • Hemoconcentration secondary to reduced plasma volume


ETIOLOGY/PATHOGENESIS


Multifactorial Causes



  • Primary erythrocytosis



    • Erythropoietin (EPO)-independent overproduction of RBCs


    • May be constitutional/familial due to inherited mutations in EPO receptor (familial primary erythrocytosis)


    • May be acquired, clonal hematopoietic stem cell disorder (polycythemia vera)


  • Secondary erythrocytosis



    • EPO-mediated


    • May be constitutional/familial due to mutations in oxygen sensing apparatus


    • May be acquired disorder with excess EPO production


    • Overproduction of EPO may be physiologically appropriate or inappropriate


    • Acquired physiologically appropriate erythrocytosis includes residence at high altitude and other chronic hypoxic conditions


    • Acquired physiologically inappropriate erythrocytoses



      • Multiple renal disorders


      • EPO-producing tumors (uterine leiomyoma, renal cell carcinoma, cerebellar hemangioblastoma, parathyroid carcinoma)


    • Drug-associated causes



      • Androgen therapy or illicit use


      • Human recombinant EPO use


  • Relative erythrocytosis



    • Hemoconcentration results from dehydration &/or excess fluid loss



      • Major causes include renal and GI disorders


    • Gaisbock syndrome


    • Hantavirus pulmonary syndrome with massive pulmonary capillary leak


Pathogenesis

Jun 13, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Acquired Erythrocytosis
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