LTF and irritable bowel syndrome: In case the patients present with symptoms suggestive of IBD, or have stool analysis results indicating abnormally high levels of calprotectin or lactoferrin, particularly in the presence of laboratory test findings or extraintestinal symptoms suggestive of IBD, upper gastrointestinal endoscopy, lower gastrointestinal endoscopy, including the terminal ileum, and histopathological examination with a mucosal biopsy are recommended.