From the Guidelines
Mild elevation in serum iron with an elevated total iron-binding capacity (TIBC) indicates iron deficiency, as the body increases production of transferrin, a protein that binds iron, in response to insufficient iron stores 1.
Key Points
- A high TIBC level suggests that there is a high amount of transferrin available to bind iron, which can indicate iron deficiency 1.
- The Transferrin Saturation (TSAT) level, which is calculated by dividing the serum iron level by the TIBC, is a more accurate indicator of iron deficiency than serum iron or TIBC alone 1.
- A TSAT level of less than 20% is often considered indicative of iron deficiency, but this threshold may not be accurate for all patients 1.
- In patients with a mild elevation in serum iron and elevated TIBC, oral iron supplementation may be recommended to replenish iron stores, with monitoring of serum iron, TIBC, and ferritin levels to assess response to treatment 1.
Important Considerations
- The distinction between absolute and functional iron deficiency is crucial in understanding the implications of a mild elevation in serum iron with elevated TIBC 1.
- Functional iron deficiency can occur in patients with adequate iron stores, but who require more iron to support erythropoiesis, such as those receiving Epoetin therapy 1.
From the Research
Serum Iron and Total Iron-Binding Capacity (TIBC) Indications
- A mild elevation in serum iron with an elevated total iron-binding capacity (TIBC) may indicate iron deficiency, as TIBC increases when iron stores are low 2, 3.
- Elevated TIBC is often seen in iron deficiency, as the body produces more transferrin to bind to the limited available iron 2.
- However, serum iron and TIBC tests may not be reliable in detecting iron deficiency, especially when ferritin levels are available 4, 3.
- Ferritin is a more accurate marker of iron stores, and its levels can help diagnose iron deficiency anemia 2, 4, 5, 3.
Relationship Between Serum Iron, TIBC, and Ferritin
- There is a poor correlation between serum ferritin levels and serum iron, TIBC, or percent transferrin saturation 4, 3.
- Serum ferritin is a more sensitive and specific marker of iron stores than serum iron and TIBC 2, 4, 5, 3.
- Elevated ferritin levels can indicate iron overload or inflammation, rather than iron deficiency 5.