A person suffers from microcytic anaemia due to deficiency of
Iron
Iron is required for the synthesis of Hb. In the deficiency of iron, Hb synthesis will be deficient making the RBCs small in shape and pale in colour. Hence the RBCs will be microcytic and hypochromic. As there will be decreased RBC count also, anaemia in iron deficiency is microcytic hypochromic anaemia.