1. OPERATIONAL IRON:
Heme attached to either hemoglobin, myoglobin, cytochromes, peroxidases, and catalases.
Heme is formed by attaching a ferrous iron atom (Fe2+) into protoporphyrin IX.
Each Hgb molecule has about 0.35% iron. This is means that 1 ml of PRBC contains about 1 mg of elemental iron.
2. STORAGE IRON
The second largest iron compartment.
Most are found in the hepatocytes. Other prominent sites include macrophages in the bone marrow, liver, and spleen.
FERRITIN- Iron is deposited in ferritin. Ferritin sequesters iron from the rest of the cell therefore preventing damage from uncontrolled oxidation.
HEMOSIDERIN- Ferritin is slowly proteolyzed within lysosomes to a non-specific complex containing iron, partially degraded protein, & lipid. This material is called hemosiderin. Hemosiderin is prominent in cells heavily loaded with iron. Hemosiderin appears to be the dead end in the metabolism of iron & ferritin. The only way the iron could be leached out of this complex is when high concentration of chelators are present.
3. LABILE IRON
4. TRANSPORT IRON