Total Iron-Binding Capacity (TIBC) Test

1. Objective

The objective of the test was to determine the total iron-binding capacity of serum, which reflected the ability of transferrin to bind iron.

2. Principle

The principle of the test was based on the fact that transferrin in serum bound iron. Excess iron was added to saturate all binding sites, and the unbound iron was removed. The concentration of iron that remained bound to transferrin was then measured. This value represented the total iron-binding capacity.

3. Materials

The materials used were:

• Patient serum sample

• Iron reagent solution (ferric chloride or ferrous ammonium sulfate)

• Buffer solution

• Precipitating reagent to remove unbound iron

• Color reagent (such as bathophenanthroline or ferrozine)

• Spectrophotometer

• Test tubes, pipettes, and centrifuge

4. Procedure (Microscopic/Analytical Steps)

1. Serum was collected from the patient.

2. Excess iron reagent was added to the serum to saturate transferrin binding sites.

3. A precipitating reagent was added to remove unbound iron, and the mixture was centrifuged.

4. The supernatant containing transferrin-bound iron was collected.

5. The bound iron was released and reacted with a chromogen (ferrozine/bathophenanthroline) to form a colored complex.

6. The absorbance was measured using a spectrophotometer at the appropriate wavelength.

7. The TIBC value was calculated from the absorbance reading and compared with standard values.

5. Result

The result was expressed in micrograms of iron per deciliter of serum (µg/dL) or micromoles per liter (µmol/L).

• Normal range: 250–450 µg/dL (44.8–80.6 µmol/L).

• Increased values indicated iron deficiency anemia.

• Decreased values indicated chronic disease, malnutrition, or liver disease.

6. Uses

The test was used to:

• Assess iron metabolism.

• Differentiate between iron deficiency anemia and anemia of chronic disease.

• Evaluate suspected iron overload or deficiency.

• Monitor treatment of iron-related disorders.

7. Consultation

If results were abnormal, consultation with a physician was recommended. The findings were usually interpreted along with serum iron and ferritin levels to provide a complete picture of iron status. Further hematological or biochemical investigations were advised if necessary.