Polycythemia

Absolute polycythemia

Erythrocytosis

Familial polycythemia

Familial polycythemia vera

Hypertonic polycythemia

Idiopathic polycythemia

Relative polycythemia

Secondary polycythemia

Secondary polycythemia due to volume depletion

Stress polycythemia

Polycythemia (also known as polycythaemia or erythrocytosis) is a disease state in which the proportion of blood volume that is occupied by red blood cells increases. Blood volume proportions can be measured as hematocrit level. It can be due to an increase in the mass of red blood cells: "absolute polycythemia"; or to a decrease in the volume of plasma, "relative polycythemia".

Familial polycythemia is a benign clinical course except for the complications of red blood cells. There are some instances in which polycythemia vera occurs in families, which results in the familial polycythemia.

For polycythemia to be reportable, the diagnosis MUST state polycythemia vera, or one of the other alternate names listed under 9950/3: Polycythemia Vera