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

    • 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

    • Polycythemia caused by altered oxygen sensing

Relative polycythemia

    • An apparent rise of the erythrocyte level in the blood

    • However, the underlying cause is reduced blood plasma

    • Causes: