The total iron-binding capacity (TIBC) is an indirect measure of which iron-related protein?

The total iron-binding capacity (TIBC) serves as an indirect measure of transferrin, which is the primary protein responsible for the transportation of iron in the bloodstream. Transferrin binds to iron and transports it to various tissues throughout the body, playing a crucial role in iron metabolism.

When there is a higher level of transferrin available, the TIBC increases, indicating a greater capacity to bind iron. This is particularly relevant in conditions where iron stores are low, as the body produces more transferrin to compensate and facilitate iron absorption and transport, reflecting the body's attempt to maintain an adequate supply of iron.

Hemosiderin and ferritin both relate to stored iron, but they do not transport iron in the way transferrin does. Hemoglobin, on the other hand, is involved in oxygen transport and, while it contains iron, it does not directly influence the measurement of TIBC. Therefore, the elevation or decrease of TIBC is specifically linked to the levels of transferrin in the body, confirming that the correct answer is indeed transferrin.