Many parts of a red blood cell are recycled when the life of a red blood cell is over. Iron is recycled and is used in new red blood cells or stored for future use as ferritin. The red blood cells distribute oxygen to all of the cells and tissues of the body. Oxygen attaches to the hemoglobin molecule of the blood cell, which consists of the protein globulin and a substance called heme that contains iron.
Red Blood Cells and Iron
A red blood cell lives for 120 days. After that time, the cell disintegrates, but some of the components of the cell are recycled. Iron, which was part of the hemoglobin of the cell, now joins with transferrin because iron travelling alone is toxic, explains John Adamson, M.D., clinical professor of medicine at the University of California in “Harrison’s Principles of Internal Medicine.” Transferrin carries iron to the bone marrow, where new red blood cells are made, and to the liver.
From Iron to Ferritin
The new red blood cells forming in the bone marrow will use the iron to make hemoglobin. Any extra iron will join with a different protein, one called apoferritin, to form ferritin. Dr. Adamson writes in “Harrison’s Principles of Internal Medicine” that inside the liver, iron leaves the transferrin protein and either joins with an enzyme or joins with apoferritin to form ferritin. Enzymes are proteins used by cells to increase the speed of biochemical reactions.
Iron and Ferritin Levels
The normal iron level for a woman is 50 to 170 micrograms/dL, while the normal range of ferritin is 10 to 120 ng/mL. For a man, 65 to 175 micrograms/dL is the normal range of iron and the normal ferritin levels are 20 to 250 ng/mL. When there is more iron than the body needs, it is deposited in the tissues, according to Eugene Frenkel, M.D., professor of internal medicine and radiology at the University of Texas Southwestern Medical Center in “The Merck Manual for Healthcare Professionals.” The medical terms for this condition are hemosiderosis, when the iron does not case any damage, and hemochromatosis when it does.
Hemosiderosis can happen when someone hemorrhages in an organ. After blood spills out of the blood vessels, iron from the red blood cells stays and accumulates in the damaged organ. Dr. Frenkel writes in “The Merck Manual for Healthcare Professionals,” that hemosiderosis usually happens in the lungs and kidneys. It happens in the lungs if someone has Goodpasture's syndrome or has hypertension in the pulmonary artery. It can affect the kidneys if blood cells are destroyed in a blood vessel, because once the damaged blood cells reach the kidneys, the iron will accumulate there.
In hemochromatosis, the extra iron accumulates and damages the tissues and organs. It is a genetic disorder usually caused by a mutation on chromosome six, per Lawrence Friedman, M.D., assistant chief of medicine at Massachusetts General Hospital in “Current Medical Diagnosis & Treatment.” Iron can accumulate in the heart, kidneys, testes, liver, adrenal gland, joints, pituitary gland, skin and pancreas. The accumulated iron may cause congestive heart failure, cirrhosis of the liver, arthritis, skin discoloration and diabetes mellitus.
- “Current Medical Diagnosis & Treatment 2011”; Stephen McPhee, M.D., Maxine Papadakis, M.D.; 2011
- “Harrison’s Principles of Internal Medicine”; Anthony Fauci, M.D., Dennis Kasper, M.D., Dan Longo, M.D. et al.; 2008
- The Merck Manual for Healthcare Professionals: Hemosiderosis