Transferrin Saturation (TS) is the percent of transferrin that has iron bound to it. The normal range is 20-50%.

TS Decreased in:

Iron Deficiency

Anemia of Chronic Disease

TS Normal in:

Thalassemias

TS Increased in:

Hemochromatosis/Iron overload

Note that TS is an early and sensitive marker of iron overload in Type I Hemochromatosis.

Transferrin Saturation (TS) is calculated by the formula:

TS = (Serum Iron / Total Iron Binding Capacity) x 100%

Serum Iron (Information)

• The serum iron assay measures the amount of circulating iron bound to transferrin in the blood
• Iron is primarily required for hemoglobin synthesis, and is necessary for the proliferation and maturation of red blood cells (erythropoiesis)
• Iron is also required for proper muscle and organ function
• Iron is intestinally absorbed and circulates in the bloodstream bound to transferrin, a protein synthesized by the liver that regulates iron absorption
• About 65% of iron is bound to hemoglobin molecules, 4% is bound to myoglobin molecules, a small amount found in cellular enzymes, and the remainder stored as ferritin or hemosiderin in the liver, bone marrow, and spleen

Total Iron Binding Capacity [(TIBC) Information]

• This test measures the total iron binding capacity as an indirect measure of transferrin concentration in the blood
• 60-70% of body's iron is transported in the blood by the plasma protein, transferrin
• Transferrin is typically 30% saturated, which means that 30% of the iron binding sites on transferrin contain an iron atom
• The TIBC is the amount of iron needed to saturate 100% of the binding sites on transferrin
• Apart from transferrin other proteins carry iron and contribute to the TIBC
• TIBC is usually measured along with serum iron and transferrin saturation as a part of full iron studies to evaluate the body's current iron storage and ability to utilized iron