A reduction in the number of red blood cells, the amount of hemoglobin, and/or the volume of packed red blood cells. Clinically, anemia represents a reduction in the oxygen-transporting capacity of a designated volume of blood, resulting from an imbalance between blood loss (through hemorrhage or hemolysis) and blood production. Signs and symptoms of anemia may include pallor of the skin and mucous membranes, shortness of breath, palpitations of the heart, soft systolic murmurs, lethargy, and fatigability.