From the Guidelines
A low total iron binding capacity (TIBC), mildly elevated iron saturation index, and normal ferritin levels suggest a condition called anemia of chronic disease (also known as anemia of inflammation), which requires a thorough evaluation to identify the underlying cause, as indicated by studies such as 1. This pattern typically occurs when the body has adequate iron stores but cannot effectively utilize them due to underlying chronic inflammation or disease.
Key Considerations
- The body's inability to utilize iron stores is often due to inflammatory cytokines increasing hepcidin production in the liver, which blocks iron release from storage sites and reduces iron absorption from the gut, creating a functional iron deficiency despite normal or even elevated iron stores 1.
- The laboratory pattern may indicate conditions such as chronic infection, autoimmune disorders, kidney disease, or certain malignancies.
- Treatment focuses primarily on addressing the underlying condition rather than iron supplementation, as iron levels are not truly deficient.
Recommended Course of Action
- Consult with a healthcare provider for a complete evaluation.
- Additional testing may include:
- C-reactive protein or erythrocyte sedimentation rate to assess inflammation.
- Complete blood count to evaluate anemia severity.
- Possibly specific tests for suspected conditions.
Important Notes
- Serum ferritin is a practical measure of body iron, but its use is limited by the influence of infection, acute and chronic inflammation, and alcohol abuse, as noted in 1.
- Transferrin saturation corresponds to the ratio of serum iron and total-iron binding capacity, but its clinical usefulness is limited by daily variability and inflammation.
From the Research
Iron Status Indicators
- Total iron binding capacity (TIBC) is a marker of protein-energy wasting (PEW) in maintenance hemodialysis (MHD) patients 2
- Low TIBC is associated with iron deficiency, PEW, inflammation, poor quality of life, and mortality 2
- TIBC or transferrin concentration alone outperforms iron and saturation indices in predicting iron deficiency 3
Diagnostic Accuracy
- Serum iron and TIBC give no additional information in the diagnosis of iron deficiency anemia and these tests are redundant for the diagnosis of iron deficiency state, if serum ferritin is available 4
- Transferrin or TIBC measurement outperforms iron and saturation in predicting iron deficiency 3
- Ferritin showed poor correlation with iron, TIBC, and transferrin saturation 4
Clinical Conditions
- Determination of TIBC from conversion of transferrin values using a constant factor results in significantly higher values compared to conversion with a function of first degree 5
- The influence of different diseases on TIBC and serum transferrin concentrations is negligible 5
- Low baseline serum TIBC is associated with iron deficiency, PEW, inflammation, poor quality of life, and mortality, and its decline over time is independently associated with increased death risk 2
Specific Scenario
- If total iron binding capacity is low, iron sat index is mildly high, and ferritin is normal, it may indicate iron deficiency or protein-energy wasting, considering the low TIBC value 2, 3
- However, the diagnostic accuracy of serum iron and TIBC in this specific scenario is limited, and ferritin is a more reliable indicator of iron status 4