Iron Transferrin and Percent Saturation |
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Iron needs of the body are met by dietary intake averaging 15 20 mg/day. Only ferrous iron can be absorbed. Transferrin is the plasma iron transport protein. Normally, it is only 20-30% saturated with iron. Transferrin bound iron is largely derived from hemoglobin breakdown. Serum iron exhibits diurnal variation, with a 20-30% decrease in the evening and day to day variations of the same magnitude. There are also diurnal and day to day variations in transferrin of 30-40% magnitude.
- Increased serum iron may be associated with hemolysis, transfusion, hemochromatosis, hemosiderosis and hepatitis. Decreased serum iron may be associated with chronic hemorrhage, dietary deficiency, anemia of chronic disease and uremia.
- Increased total iron binding capacity (or transferrin) may be associated with iron deficiency, hepatitis, pregnancy and the administration of estrogen.
- Decreased total iron binding capacity may be associated with pernicious anemia, hemochromatosis, uremia, acute and chronic inflammation and protein malnutrition.
Reference range is 50 150 mg/dL for serum iron and 170 - 340 mg/dL for transferrin. Percent saturation is calculated with the following formula: Iron/transferrin x 1.2. The percent saturation reference range is 15 - 50%.
Specimen requirement is one SST tube of blood.
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