A 37-year-old woman presents with chronic diarrhoea and weight loss. Blood tests show microcytic anaemia and tissue transglutaminase (tTG) antibodies are strongly positive. What is the next most appropriate step?AStart a gluten-free diet immediately and arrange review in 6 monthsBRefer for upper GI endoscopy with duodenal biopsy while continuing a gluten-containing dietCOrder colonoscopyDStart oral Iron onlyEReassure that this is likely IBSCheck my answer