This study is a randomized controlled trial of preoperative oral iron supplementation, to identify whether iron deficiency is a modifiable risk factor for adverse surgical outcomes such as red blood cell transfusion and diminished postoperative cognitive and physical capacity in adolescents undergoing scoliosis surgery. Research Question(s)/Hypothesis(es): Primary * Iron supplementation will reduce the incidence of perioperative RBC transfusion in iron deficient scoliosis patients undergoing spinal fusion. Secondary * Iron supplementation will reduce postoperative neurocognitive functional declines in iron deficient scoliosis patients undergoing spinal fusion. * Iron supplementation will improve patient-reported physical functioning in iron deficient scoliosis patients undergoing spinal fusion.