Iron deficiency vs thalassemia trait

Dimension	Iron deficiency	Thalassemia trait
Iron studies	Ferritin low, TSat low, TIBC high	Normal
Red cell count	Low or normal	Normal or high despite anemia
MCV for the degree of anemia	Proportionate	Disproportionately low
Response to iron	Corrects	None; iron accumulates
Confirmation	Ferritin (and a cause for the loss)	Hemoglobin electrophoresis (beta) or genetics (alpha)

Pearls

Giving iron to thalassemia trait treats a number and loads an organ; make the distinction first.
The two coexist; iron studies still read correctly in trait carriers.

Connected