You probably all know this already, but I was filling in my iron knowledge gaps. I think this explains thing fairly well.
Source:
http://www.ccmh.net/Services/Wellness/Need_Help_Understanding_Your_Results.aspx
Iron Function
IRON The body must have iron to make hemoglobin and to help transfer oxygen to the muscles.
Optimal Range: 49-151 ug/dL
If the body is low in iron, all body cells, particularly muscles in adults and brain cells in children, do not function as well as they should. On the other hand too much iron in the body can cause injury to the heart, pancreas, joints, testicles, ovaries, etc. Iron excess is found in the hereditary disease called hemochromatosis which occurs in about 3 out of every 1000 people. Any value outside the specified reference range should be evaluated by your health care provider.
TOTAL IRON BINDING CAPACITY (TIBC) lron is transported in your blood bound to a protein called transferrin. Transferrin transports the iron in your body from the iron storage sites to where it is needed. It also transports the iron, when not needed, back to the storage sites.
Optimal Range: 260-400 ug/dL
A lower IBC suggests malnutrition or iron excess. A high IBC suggests iron deficiency.
IRON SATURATION INDEX is obtained by comparing the iron level to the TIBC level. It is a simple way to compare the amount of iron in the blood to the capacity of the blood to transport iron.
Optimal Range: 15-50%
FERRlTlN is measured if the iron saturation index is low or high. Ferritin is the chief storage form of iron in the body.
Optimal Range: 30-400 ng/ml
The level is low in iron deficiency and is high in iron excess, inflammation, and liver disease.
