Includes:

• Fe and TIBC
• TIBC and Iron
• Total Iron-binding Capacity (TIBC)
• Transferrin Saturation
• Unsaturated Iron-binding Capacity (UIBC)

Use

Used in the  differential diagnosis of anemia (as reviewed below), especially with hypochromia and/or low MCV. The percent saturation sometimes is more helpful than is the iron result for iron deficiency anemia. Evaluate thalassemia and possible sideroblastic anemia; work-up hemochromatosis, in which iron is increased and iron saturation is high. Decrease in iron level after performance of Schilling supports the diagnosis of vitamin B₁₂ deficiency, vide infra. Evaluate iron poisoning (toxicity) and overload in renal dialysis patients, or patients with transfusion dependent anemias. Use of TIBC in iron toxicity may be less useful than previous believed. TIBC or transferrin is a useful index of nutritional status.

Uncomplicated iron deficiency: Serum transferrin (and TIBC) high, serum iron low, saturation low. Usual causes of depleted iron stores include blood loss, inadequate dietary iron. RBCs in moderately severe iron deficiency are hypochromic and microcytic. Stainable marrow iron is absent. Serum ferritin decrease is the earliest indicator of iron deficiency if inflammation is absent.

Anemia of chronic disease: Serum transferrin (and TIBC) low to normal, serum iron low, saturation low or normal. Transferrin decreases with many inflammatory diseases. With chronic disease there is a block in movement to and utilization of iron by marrow. This leads to low serum iron and decreased erythropoiesis. Examples include acute and chronic infections, malignancy and renal failure.

Sideroblastic anemia: Serum transferrin (and TIBC) normal to low, serum iron normal to high, saturation high.

Hemolytic anemias: Serum transferrin (and TIBC) normal to low, serum iron high, saturation high.

Hemochromatosis: Serum transferrin (and TIBC) slightly low, serum iron high, saturation very high.

Protein depletion: Serum transferrin (and TIBC) may be low, serum iron normal or low (if patient also is iron deficient). This may occur as a result of malnutrition, liver disease, renal disease (eg, nephrosis) or other entities.

Liver disease: Serum transferrin variable; with acute viral hepatitis, high along with serum iron and ferritin. With chronic liver disease (eg, cirrhosis), transferrin may be low. Patients who have cirrhosis and portacaval shunting have saturated TIBC/transferrin as well as high ferritin.

Chronic dialysis for renal failure: monitor iron levels in patients undergoing dialysis. To follow treatment of iron overload with deferoxamine or with regimen of recombinant human erythropoietin and phlebotomy.

NOTE: Ferritin levels are also useful for iron deficiency. Low iron level may not indicate iron deficiency in acute infection with leukocytosis. Low iron levels may be misleading in chronic infection, inflammation and malignancy; high ferritin levels occur in many such states, however, the most sensitive test for iron deficiency is bone marrow examination. TIBC and transferrin are increased in patients on oral contraceptives, with normal saturation. Gross hemolysis may interfere with serum iron.

Preparation 

Iron levels on patients who have had blood transfusions should be delayed for at least four days.