In the iron binding capacity (TIBC) assay, what is the normal saturation of transferrin with iron?

In the iron binding capacity (TIBC) assay, what is the normal saturation of transferrin with iron?

• A. 10 percent
• B. 30 percent
• C. 60 percent
• D. 100 percent

Answer: (B)

Transferrin saturation tells us what fraction of transferrin’s iron‑binding sites are currently occupied by iron. In healthy individuals, transferrin is not fully loaded with iron; roughly one‑third of its binding sites are occupied, giving a normal transferrin saturation around 30%. The TIBC test measures how much iron transferrin can bind, reflecting the available binding capacity, not the actual iron bound at any moment. Because normal physiology has only about 30% of sites occupied, a value around 30% best fits the typical state. Higher saturation, like 60% or 100%, would suggest excessive iron binding, while 10% would be unusually low. So the normal saturation of transferrin with iron is about 30%.

Transferrin saturation tells us what fraction of transferrin’s iron‑binding sites are currently occupied by iron. In healthy individuals, transferrin is not fully loaded with iron; roughly one‑third of its binding sites are occupied, giving a normal transferrin saturation around 30%.

The TIBC test measures how much iron transferrin can bind, reflecting the available binding capacity, not the actual iron bound at any moment. Because normal physiology has only about 30% of sites occupied, a value around 30% best fits the typical state. Higher saturation, like 60% or 100%, would suggest excessive iron binding, while 10% would be unusually low.

So the normal saturation of transferrin with iron is about 30%.