TIBC

DESCRIPTION:
Transferrin can now be determined by immunochemical methods (RID, nephelometric, turbidimetric). However, transferrin is more commonly measured via bound iron as TIBC or UIBC. Trivalent iron is ionically bound to transferrin. 1.25 mg of iron binds to 1 mg of protein at pH > 6.5. TIBC (Total Iron Binding Capacity), the total iron binding capacity, is a measure of transferrin concentration – the protein that carries iron in serum. Transferrin concentration in normal serum is 2.0-4.0 g/L, but it is not completely saturated with iron (only 1/3 of transferrin is saturated with iron, figure), so we distinguish between total iron binding capacity (TIBC) and unsaturated iron binding capacity (UIBC). When determining iron concentration, iron must first be separated from transferrin, then converted from trivalent to divalent form, and a colored reaction performed using a specific reagent.

DETERMINATION:
TIBC is determined by photometric method. Ferric chloride solution (iron III) is added to serum to saturate all transferrin. Excess iron ions are removed by binding to aluminum oxide, after which iron concentration is determined. The sample for analysis must not be hemolyzed. The sample for analysis is serum or plasma (EDTA). Sample stability is 7 days at 4°C, 4 days at 15°C to 25°C.

CLINICAL SIGNIFICANCE:
Elevated TIBC and UIBC values are of great importance for differential diagnosis of anemias caused by iron deficiency or infection or tumor. 1) Physiological variations of TIBC In infants, TIBC decreases after birth, then increases and reaches values up to 71.6 mmol/L / In normal pregnancy, TIBC increases to approximately 80.1 mmol/L, while iron concentration decreases. UIBC is elevated in pregnant women. 2) Pathological changes in TIBC in: A) Increased values Active portal cirrhosis / Acute and subacute liver necrosis / Acute hepatitis / Acute and chronic blood loss / Acute tonsillitis / Iron deficiency anemia / Ancylostomiasis / Benign gastric neoplasm / Celiac disease / Hemochromatosis / Hemolytic anemia / Renal carcinoma / Rectal carcinoma / Gastric carcinoma / Chronic active hepatitis / Hereditary spherocytosis / Peptic ulcer / Strongyloidiasis / Thalassemia minor and major / Ulcerative colitis / Viral hepatitis / Whipple’s disease B) Decreased TIBC values in: Acute and chronic infection / Anemia of chronic disease / Vitamin B6 deficiency anemia / Iron deficiency anemia / Aplastic anemia / Liver cirrhosis / Folic acid deficiency / Hypothyroidism / Hodgkin’s disease / Renal carcinoma / Lung carcinoma / Uterine carcinoma / Kwashiorkor / Malaria / Tumor metastases / Nephrotic syndrome / Non-Hodgkin’s lymphoma / Pernicious anemia in relapse / Congenital transferrinemia / Protein malnutrition / Rheumatoid arthritis / Septicemia / Sideroblastic anemia / Scurvy / Uremia

RISK FACTORS:
Decreased values:
Alcoholism Malnutrition Menstrual cycle After surgical procedures (hysterectomy or gastrointestinal surgery)
Increased values:
Iron-rich food with low phosphate content

DRUG EFFECTS:
Increased values:
Iron dextran complex

RESULTS:
Reference interval depends on sex, age, and reference interval. Reference interval is displayed on each validated result.