Anemia caused by iron deficiency occurs when the body does not have enough iron. Anemia is characterized by a low number of red blood cells. The red blood cells contain hemoglobin, a protein that transports oxygen throughout the body. Hemoglobin is made by the body using an iron. A lack of iron leads to a reduction in hemoglobin and red blood cells, which causes anemia. In children, hemoglobin and hematocrit are often the first screening tests for anemia. Hemoglobin and red blood cells are measured. Red and white blood cells, blood clotting cells (platelets), and young red blood cells (reticulocytes) are all checked during a complete blood count. Hemoglobin and hematocrit are included, along with more details about the red blood cells. During peripheral smears, a small sample of blood is examined under a microscope. The blood cells are examined to determine if they are normal. An iron study is a blood test that can determine how much iron is in your child.