From the Guidelines
Low Total Iron-Binding Capacity (TIBC) indicates a condition where the body's ability to transport iron in the blood is reduced, often associated with iron overload, liver disease, malnutrition, or inflammation. This condition can be caused by various factors, including:
- Iron overload (hemochromatosis) 1
- Liver disease 1
- Malnutrition 1
- Inflammation 1 The measurement of TIBC specifically refers to the decreased capacity of transferrin, the main iron-carrying protein in blood, to bind to iron. Normal total iron binding capacity (TIBC) ranges from 240-450 mcg/dL, with lower values suggesting these underlying conditions 1. This finding is often evaluated alongside serum iron levels and transferrin saturation to provide a complete picture of iron status 1. If you have low iron binding capacity, your healthcare provider may recommend additional tests to determine the underlying cause, such as genetic testing for hereditary hemochromatosis 1, liver function tests 1, or inflammatory markers. Treatment depends on identifying and addressing the root cause rather than the low binding capacity itself 1. The body carefully regulates iron because it's essential for oxygen transport and cellular function, but excess iron can be toxic to tissues, particularly the liver, heart, and endocrine organs 1. According to the most recent guidelines 1, the first step in testing for haemochromatosis is the assessment of serum iron parameters, which should include transferrin saturation and serum ferritin. The concentration of serum iron and transferrin or total iron binding capacity can provide additional information for the differential diagnosis 1. Biochemical findings that indicate haemochromatosis with iron overload include elevated transferrin saturation, high ferritin, and elevated liver transaminases 1.
From the Research
Low Total Iron-Binding Capacity (TIBC) Indications
- Low TIBC (< 200 μg/dL) is associated with hypoalbuminemia and high C-reactive protein, as seen in patients with chronic kidney disease (CKD) 2
- Low TIBC is also linked to iron deficiency, protein-energy wasting (PEW), inflammation, poor quality of life, and mortality in hemodialysis patients 3
- A decline in TIBC over time is independently associated with increased death risk in hemodialysis patients 3
- Low TIBC may indicate malnutrition and inflammation, which can affect iron status and increase the risk of anemia 2, 3
- TIBC measurements may be preferred over transferrin concentration in non-European populations with marked genetic variation in transferrin 4
Comparison with Other Iron Status Markers
- Unbound iron binding capacity (UIBC) may be a more accurate marker of empty iron stores than serum transferrin saturation, with a better diagnostic accuracy than s-iron, s-transferrin, and s-transferrin saturation 5
- TIBC has a strong positive correlation with serum transferrin levels, especially when measured by direct method 6
- However, TIBC methods may overestimate the iron binding capacity of transferrin due to binding of iron to other plasma proteins, such as albumin 4