The earliest sign of iron deficiency anaemia -

<p>Plasma ferritin is a measure of iron stores in tissues & is the single test to confirm iron deficiency .It is a very specific test. In the course of development of anaemia, firstly storage iron(ferritin) depletion occurs during which iron reserves are lost without compromise of the iron supply for erythropoiesis.</p><p>Plasma iron & total iron binding capacity(TIBC) are measures of iron availability ;hence they are affected by many factors besides iron stores.Plasma iron has a diurnal & day -to-day variation & becomes very low in acute phase response .</p>