Polycythemia

Introduction

• • Disease state in which the proportion of blood volume that is occupied by red blood cells increases

  • May be due to:

    • an increase in the mass of red blood cells ("absolute polycythemia")

    • a decrease in the volume of plasma ("relative polycythemia")

Absolute polycythemia

• • Primary polycythemia

    • Due to factors intrinsic to red cell precursors

    • Polycythemia vera (PCV)

      • Occurs when excess red blood cells are produced as a result of an abnormality of the bone marrow

      • Often, excess white blood cells and platelets are also produced

      • Classified as a myeloproliferative disease

    • Primary familial polycythemia, Primary familial and congenital polycythemia (PFCP)

      • Benign hereditary condition

      • Possibly due to a dominant mutation in the erythropoietin receptor

  • Secondary polycythemia

    • Caused by either natural or artificial increases in the production of erythropoietin

    • Called physiologic polycythemia if the increase is appropriate

      • Altitude related

      • Hypoxic disease associated

      • Iatrogenic

      • Genetic

        • Associated with abnormalities in hemoglobin oxygen release

    • Can also be pathological

      • Neoplasms

        • Renal or liver tumors, hemangioblastomas in the central nervous system

      • Endocrine abnormalities including pheochromocytoma and adrenal adenoma with Cushing's syndrome

      • People whose testosterone levels are high because of the use anabolic steroids

  • Polycythemia caused by altered oxygen sensing

    • Inherited mutations in genes which all result in increased stability of Hypoxia Inducible Factors (HIFs)

      • Chuvash polycythemia

      • PHD2 erythrocytosis

      • HIF2α erythrocytosis

Relative polycythemia

• • An apparent rise of the erythrocyte level in the blood

  • However, the underlying cause is reduced blood plasma

  • Causes:

    • Loss of body fluids, such as through burns, dehydration and stress

    • Can be caused by apparent polycythemia also known as Gaisböck's syndrome

    • Apparent polycythemia primarily affects middle-aged obese men

      • Associated with smoking, increased alcohol intake and hypertension.[13]