Serum Iron & TIBC Test

This combined test measures two related but distinct values: serum iron, the amount of iron currently circulating and bound to transport proteins in your blood, and TIBC (Total Iron Binding Capacity), which reflects your blood's overall capacity to carry iron.

Together, these values — often reported alongside a calculated transferrin saturation percentage — help your doctor understand not just how much iron is present, but how your body's iron transport system is behaving.

This distinction matters clinically because low serum iron can result from either true iron deficiency or from chronic inflammatory disease that traps iron away from circulation, and TIBC helps tell these two very different situations apart.

The test is usually ordered as part of a broader anemia workup rather than as a standalone test, since its real value comes from being interpreted alongside ferritin and a complete blood count.