<unk>  is defined an increase in the relative number of red blood cells in a unit volume of plasma resulting from either a decrease in plasma volume (due to dehydration for instance) or increased production of erythrocytes (due to polycythemia vera for instance).
Hemoconcentration
Osmotic diuresis
Enuresis
Diuresis
Third spacing of fluids
Hypervolemia
Rebound diuresis
Kaliuresis