What is the principal cause of low serum iron and high total iron-binding capacity?

The principal cause of low serum iron and high total iron-binding capacity is iron deficiency anemia. This condition occurs when the body does not have sufficient iron to produce hemoglobin, the protein in red blood cells that carries oxygen. As the iron stores deplete, serum iron levels drop significantly.

In response to low iron levels, the body increases the production of transferrin, a protein that binds iron and transports it in the bloodstream. This increase in transferrin leads to a higher total iron-binding capacity (TIBC), which is a measure of the blood’s capacity to bind iron with transferrin. Therefore, the presence of low serum iron alongside elevated TIBC strongly indicates that the body is attempting to mobilize more iron due to a deficiency.

In contrast, conditions like hepatitis or nephrosis may not exhibit the same pattern because they could cause changes in iron metabolism without the same degree of iron deficiency or alteration in transferrin production. Noniron deficiency anemias also present differently in terms of serum iron and TIBC values, typically not showing a marked increase in TIBC as seen in iron deficiency cases.