Human Iron Metabolism - How Cells Get Their Iron From The Body

How Cells Get Their Iron From The Body

As discussed above, 60% or more of the iron in the body is located in hemoglobin molecules of red blood cells, and much of the rest is in ferritin storage form in the liver and other places, the amount of this varying widely between persons. When red blood cells reach a certain age, they are degraded and engulfed by specialized scavenging macrophages. These cells internalize the iron-containing hemoglobin, degrade it, put the iron onto transferrin molecules, and then export the transferrin-iron complexes back out into the blood. Most of the iron used for blood cell production comes from this cycle of hemoglobin recycling.

All cells use some iron, and must get it from the circulating blood. Since iron is tightly bound to transferrin, cells throughout the body have receptors for transferrin-iron complexes on their surfaces. These receptors engulf and internalize both the protein and the iron attached to it through receptor-mediated endocytosis. Once inside, the cell transfers the iron to ferritin, the internal iron storage molecule which is present in all cells.

Transferrin receptor production will increase, and ferritin production will decrease.