Which organ is primarily involved in the breakdown and recycling of old red blood cells?

• A. Liver
• B. Spleen
• C. Kidney
• D. Pancreas

Answer: (B)

Old red blood cells are removed mainly by macrophages in the spleen’s red pulp. This is where aged erythrocytes are phagocytosed in a process called extravascular hemolysis, initiating their breakdown and recycling. Inside the macrophages, globin is recycled into amino acids, iron is salvaged and returned to the bone marrow for new hemoglobin, and the heme portion is converted to bilirubin, which is then carried to the liver for processing and excretion. The liver helps finish bilirubin processing, but the primary site of breakdown and recycling of old RBCs is the spleen. The kidney doesn’t perform RBC destruction, and the pancreas is unrelated to this turnover.