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.



  • Polycythemia


  • 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


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


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