Cyanosis is not seen in severe anemia because?

Cyanosis is not seen in severe anemia because a critical concentration of reduced hemoglobin is required. Cyanosis Bluish discoloration of skin & mucous membranes due to an increased quantity of reduced Hb (i.e., deoxy Hb) or Hb derivatives (e.g., met Hb or sulfhemoglobin) in the small blood vessels. Cyanosis becomes apparent when the concentration of reduced hemoglobin in capillary blood > 4 g/dL. Absolute, rather than the relative, quantity of reduced Hb that is impoant in producing cyanosis. = In a patient with severe anemia, the relative quantity of reduced Hb in the venous blood may be very large, but the absolute quantity of reduced Hb is still small. = Therefore, patients with severe anemia & even marked aerial desaturation may not display cyanosis.