Background

The iron binding capacity is the measure of ability of the blood to bind iron with transferrin. The total iron-binding capacity (TIBC) is a method used to indirectly evaluate transferrin level. 

TIBC is related to serum transferrin level. The relation is not straight. TIBC and UIBC (unsaturated binding capacity) is not same. UIBC measures how much iron is left without binding with the transferrin.  

Increased level of iron conditions can lead to elevated percentage of saturation of transferrin with iron. These conditions include iron poisoning, sideroblastic anemia, hemolytic anemia, hemochromatosis, thalassemia, aplastic anemia, and pyridoxine deficiency. 

Decreased level of iron can lead to reduced percentage of saturation of transferrin. It is usually below 16%. Transferrin is also used to know about the nutritional status. Test result may affect by the current transfusions. 

A decreased level of TIBC for 6 months is associated with a fatal hazard ratio. In this, the level of TIBC is above 20 mg/dL and the ratio is 1.57. Low level of serum TIBC is linked to the deficiency in iron, malnutrition in protein, inflammation, increased risk of death, and a low quality of life. A decreased level of TIBC is associated with an increased risk of mortality. 

As per the study of the Ikeda-Taniguchi, patients who are having regular hemodialysis have a connection with reduced muscle mass and albumin and TIBC in lower tertiles. 

Indications/Applications

TIBC is used to diagnose the anemia, to screen the increased level of iron, in conditions like late pregnancy and acute hepatitis and to measure the saturation percentage to diagnose the iron deficiency. 

The symptoms which are associated with the increased or decreased level of the iron binding capacity like: 

Weakness 

Tiredness 

Pale skin 

Feel cold 

Frequent sicking 

Swollen tongue 

Stomach and joint pain 

Clinical significance: 

The TIBC is an indicator of the transferrin which is present in the circulating blood. About one third of the transferrin saturated with the iron. The UIBC is assessed by spectrophotometric or radioactive iron methods. The total of the plasma iron and UIBC is the TIBC. TIBC is also measured directly.  

Oral contraceptives and estrogen increase TIBC. Testosterone, asparaginase, corticotrophin, chloramphenicol, and cortisone decrease the TIBC. 

Iron deficiency anemia disease increase the UIBC and TIBC. The transferrin saturation is about 15% or less. Patients who have chronic inflammation anemia have low level of iron and normal saturation of transferrin. 

Reference Range

The normal level of TIBC is 255 to 450 μg/dL. 

Interpretation

The conditions which are associated with the increased level of iron binding capacity like: 

Deficiency in iron 

Late pregnancy 

Progesterone birth control pills 

Acute liver damage 

Acute and chronic blood loss 

The conditions which are associated with the decreased level of iron binding capacity like: 

Nephrotic disease 

Anemia of chronic diseases 

Hyperthyroidism 

Hemosiderosis 

Thalassemia 

Hemochromatosis 

Collection And Panels

Collection: 

Sample type: Blood 

Sample collection method: Venipuncture 

Container: Red top tube or tiger top tube 

Considerations: Before collecting the sample, 8 hours fasting is required. 

Panels: 

Serum iron panel 

Complete blood count (CBC) test 

Hematocrit test 

Hemoglobin test 

Modifying factors: 

Some medications and compounds affect the test result. This may include alcohol, birth control pills, estrogen, testosterone, aspirin, antibiotics, and cortisone. During the menstruation cycle, the iron level gets decreased. This also affects the test result. 

References

https://www.ncbi.nlm.nih.gov/books/NBK559119/