A 38-year-old woman from Mumbai presents with progressive fatigue and dyspnea for 3 months. On examination, she has mild splenomegaly. Her CBC shows Hb 7.2 g/dL, MCV 72 fL, and RBC count 5.8 × 10¹²/L. Peripheral blood smear reveals microcytic RBCs with target cells, polychromasia, and occasional nucleated RBCs. Serum ferritin is 1200 ng/mL and serum iron is elevated. What is the most appropriate next step in management?