A 68-year-old man presents with fatigue and exertional dyspnoea. Full blood count shows haemoglobin 95 g/L, mean corpuscular volume 70 fL and low ferritin. What is the most appropriate next step in management?AStart oral iron and no further investigationBArrange colonoscopy and gastroscopy to investigate for gastrointestinal blood lossCOrder serum B12 and folate onlyDReassure and repeat bloods in 12 monthsETransfuse red cells and discharge without further workupCheck my answer