TIBC measures the serum iron transporting capacity of which protein?

TIBC measures the serum iron transporting capacity of which protein?

• A. Transferrin
• B. Ferritin
• C. Hemoglobin
• D. Myoglobin

Answer: (A)

Total iron-binding capacity measures the serum iron–binding capacity provided mainly by transferrin, the primary iron transport protein in blood. Transferrin carries iron through the bloodstream to tissues that need it, so TIBC essentially reflects how much iron could be bound by these transport molecules. Ferritin stores iron inside cells and serves as a marker of iron stores, not transport capacity. Hemoglobin and myoglobin bind and carry iron within cells or muscles, not in the serum as transport proteins. Therefore, transferrin is the protein whose capacity is reflected by TIBC.

Total iron-binding capacity measures the serum iron–binding capacity provided mainly by transferrin, the primary iron transport protein in blood. Transferrin carries iron through the bloodstream to tissues that need it, so TIBC essentially reflects how much iron could be bound by these transport molecules. Ferritin stores iron inside cells and serves as a marker of iron stores, not transport capacity. Hemoglobin and myoglobin bind and carry iron within cells or muscles, not in the serum as transport proteins. Therefore, transferrin is the protein whose capacity is reflected by TIBC.