Composite image of normal (top) and iron-deficient (bottom) blood cells. Top image: Color-enhanced light micrograph of human red blood cells and platelets. Magnification 400x. Bottom image: Light micrograph of red blood cells from a patient suffering from iron-deficiency anemia. This is caused by a lack of iron, an essential component of hemoglobin, the oxygen-carrying pigment of red blood cells (erythrocytes). The red blood cells in iron-deficiency anemia are smaller and paler than normal. The lack of iron may be due to a loss of blood, through a digestive disorder such as a stomach ulcer or heavy menstrual periods. Alternatively there may be a lack of iron in the diet. Symptoms include tiredness, dizziness and pale skin. Composite of BT6804 and BL4804.