Transferrin formula

• A. Transferrin (mg/dL) = TIBC × 0.7
• B. Transferrin (mg/dL) = TIBC ÷ 2
• C. Transferrin (mg/dL) = TIBC + 5
• D. Transferrin (mg/dL) = TIBC − 20

Answer: (A)

The key idea is how transferrin concentration relates to TIBC. TIBC reflects the total iron-binding capacity in serum, which essentially comes from the amount of transferrin present and its binding sites. In practice, the transferrin concentration in mg/dL is about two-thirds of the TIBC expressed in μg/dL, so a commonly used conversion is Transferrin mg/dL ≈ TIBC μg/dL × 0.7. This simple factor links the binding capacity to the actual protein amount. For example, if TIBC is 300 μg/dL, the estimated transferrin would be about 210 mg/dL, which fits typical physiological ranges. The other proposed operations (dividing by 2, adding or subtracting a constant) don’t reflect how binding capacity scales with transferrin concentration, so they don’t align with the standard relationship.