Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1033 page)

   Ingestion of iron (including iron-fortified vitamins or supplements) may cause transient elevated iron levels.

IRON-BINDING CAPACITY, TOTAL (TIBC)

   Definition

   TIBC measures the blood’s capacity to bind iron with transferrin (TRF). One milligram of TRF binds to 1.25 μg of iron, and, therefore, a serum TRF level of 300 mg/dL is equal to TIBC of (300 × 1.25) 375 μg/dL. TIBC is an indirect way of assessing TRF level. TIBC correlates with serum TRF, but the relationship is not linear over the wide range of TRF values and is disrupted in diseases affecting transferrin-binding capacity and iron-binding proteins. TIBC should not be confused with unsaturated binding capacity (UIBC), where UIBC = TIBC minus serum iron (μg/dL).

   
Normal range:
255–450 μg/dL.

   Use

   Differential diagnosis of anemias

   Should always be performed whenever serum iron is done to calculate percent saturation for diagnosis of iron deficiency

   Screening for iron overload

   Acute hepatitis

   Late pregnancy

   Interpretation

Increased In

   Iron deficiency

   Acute and chronic blood loss