Iron is needed to help form adequate numbers of normal red blood cells, which carry oxygen throughout the body. Iron is a critical part of hemoglobin, the protein in red blood cells that binds oxygen in the lungs and releases it as blood travels to other parts of the body. Low iron levels can lead to anemia, in which the body does not have enough red blood cells. Other conditions can cause too much iron to accumulate in your body. This can produce damage to several organs, including the liver, heart, and pancreas. Iron status is evaluated by several tests that are not always run together. These include: Serum iron - measures the level of iron in the liquid part of your blood. Total Iron Binding Capacity (TIBC) - measures the amount of iron that can be carried through blood by transferrin. Transferrin is the protein that transports iron from the gut to the cells that use it. Your body makes transferrin in relationship to your need for iron; when iron stores are low, transferrin levels increase and vice versa. In healthy people, about one-third of the binding sites on transferrin are used to transport iron. This number is called the transferrin saturation.