Assay

Unsaturated Iron Binding Capacity

Key Words

UIBC, TIBC, ISAT

Specimen Collection

Serum (brown) Plasma (orange)

Turnaround Time

24hrs

Test Indications

The sum of the serum iron and UIBC represents total iron-binding capacity (TIBC). TIBC is a measurement for the maximum iron concentration that transferrin can bind. The serum TIBC varies in disorders of iron metabolism. In iron-deficiency anaemia the TIBC is elevated and the transferrin saturation is lowered to 15 % or less. Low serum iron associated with low TIBC is characteristic of the anaemia of chronic disorders, malignant tumours, and infections. Iron saturation is used as a follow-up test in patients with elevated ferritin. Please note: ferritin is recommended in the assessment of iron status

Interferences

Haemolysis invalidates the test as erythrocytes contain an increased concentration of the analyte compared to sera. Common drugs caused no significant interference except oxytetracycline which causes artificially high UIBC values. Complexing anticoagulents (e.g. EDTA, citrate) cause assay interference. Pathologically high levels of albumin (70 g/L) decrease the apparent UIBC value significantly. If the patients serum iron exceeds the binding capacity of the transferrin, a negative UIBC value will result. In patients treated with iron supplements or metal-binding drugs, the drug-bound iron may not properly react in the test, resulting in falsely low values. The physiological function of deferoxamine containing drugs is to bind iron to facilitate its elimination from the body. Therefore any deferoxamine concentration interferes with the UIBC assay.

Reference Range

•       Females: 24.2-70.1 umol/L

•       Males: 22.3-61.7 umol/L

Analytical Error

8.2%

Reference Change Value

N/A

Minimum retesting interval

Requests made within 28 days of a previous result on a patient are intervened