juice82

As I understand it, serum iron does count. The interplay of ferritin, transferrin saturation, and serum iron is the important thing. Ferritin is a hollow protein that binds up lots of iron molecules - thousands per each ferritin molecule - and stores the iron in cells for later use. Transferrin is a protein in the blood that carries around 2 iron molecules per transferrin protein. When transferrin meets up with its receptor (transferrin receptor) on the surface of a cell, the iron can be transported into the cell where ferritin ought to grab hold of it.

If you have excess iron in the blood or cells that isn't being handled by transferrin and/or ferritin, I believe this has potential to cause problems. It becomes a free radical, doing oxidative damage. When transferrin becomes over-saturated (too many transferrin molecules with iron bound to it) then there is too much free iron in the blood. If the transferrin receptor isn't working properly, then the iron isn't getting into the cells for storage in ferritin. It's complicated - and to get a good picture of what's going on, all iron parameters should be looked at. Something can go wrong at one of the many different points in iron metabolism.