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Red blood cells (RBCs) are perhaps the most recognizable component of whole blood. RBCs contain hemoglobin, a complex iron-containing protein that carries oxygen throughout the body and gives blood its red color. The percentage of blood volume composed of red blood cells is called the "hematocrit." The average hematocrit in an adult male is 47 percent. There are about one billion red blood cells in two to three drops of blood, and for every 600 red blood cells, there are about 40 platelets and one white cell. RBCs may be treated and frozen for extended storage, up to 10 years. Manufactured in the bone marrow, RBCs are continuously produced and broken down. They live for about 120 days in the circulatory system and are eventually removed by the spleen. Red blood cells are prepared from whole blood by removing the plasma, or the liquid portion of the blood, and can raise the patient's hematocrit and hemoglobin levels while minimizing an increase in blood volume. Patients who benefit most from transfusions of red blood cells include those with chronic anemia resulting from kidney failure, malignancies or gastrointestinal bleeding and those with acute blood loss resulting from trauma. Since red blood cells have reduced amounts of plasma, they are well-suited for treating anemia patients who would not tolerate the increased volume provided by whole blood, such as patients with congestive heart failure or those who are elderly or debilitated.
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