A source for healthcare professionals to access the latest data and information on the diagnosis, treatment and management of patients with gut related disorders


Diagnostic process in functional bowel disorders

Dr Fermín Mearin-Manrique

Director of the Department of Gastroenterology, Institute of Functional and Motor Digestive Disorders, Barcelona, Spain

The complementary tests to perform in the investigation of functional bowel disorders must be chosen in accordance with the individual characteristics of each patient, including age, evolution period of the symptoms, presence of warning signs and findings from physical examinations.1

The routine laboratory analyses (blood count and biochemistry) in patients with a functional bowel disorder (FBD) are normal. The general analytical tests which are recommended for the initial study of a patient with diarrhoea-predominant irritable bowel syndrome (IBS-D) or functional diarrhoea are blood count to exclude anaemia or leukocytosis,1 anti-transglutaminase antibodies and serum IgA levels to exclude coeliac disease,2,3 as well as the assessment of C-reactive protein (CRP) and faecal calprotectin to exclude the possibility of inflammatory bowel disease.1 If intestinal infections are suspected, a faecal parasite study such as giardiasis, should be requested.1

Patients with signs or symptoms of medical issues that accompany diarrhoea (anaemia, leukocytosis, elevated CRP, elevated calprotectin), recent onset of clinical symptoms, aged over 50, or with a family history of polyposis or colon cancer, should undergo a colonoscopy.1 It is important to remember that during a colonoscopy it is obligatory to examine the terminal ileum to evaluate the possible existence of an inflammatory intestinal disease, and multiple biopsies must be taken to exclude microscopic colitis.2,4

The performance of other complementary tests will depend on clinical suspicion, for example investigation of thyroid function is indicated when there are other accompanying symptoms or a family history of thyroid diseases.1 Breath tests are used to diagnose intestinal bacteria overgrowth disorder, lactose intolerance, insufficient pancreatic exocrine function, etc.1,2


Dr Fermín Mearin-Manrique is Director of the Department of Gastroenterology at the Teknon Medical Center, Barcelona, Spain. Doctor Cum Laude at the Autonomous University of Madrid, Dr Mearin-Manrique has experience in professional and research centre of excellence including the Mayo Clinic in the United States and the Hospital Vall d'Hebron in Barcelona. He is the ex-President of the Spanish Gastroenterology Association and the author of numerous renowned Spanish and international scientific papers, such as the Rome IV criteria.


1. Lacy B et al. Gastroenterology 2016;150:1393–1407.
2. Mearin F & Lacy B. Neurogastroenterol Motil 2012;24:791–801.
3. Ford A et al. Arch Intern Med 2009;169:651–658.
4. Guagnozzi D et al. Aliment Pharmacol Ther 2016;43:851–862.

Job number: JB57410GBj Date of Preparation: June 2019

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