Not everyone with potential irritable bowel syndrome requires extensive endoscopic investigation; e.g. both upper GI endoscopy and small bowel biopsy and colonoscopy. A patient who is young and has symptoms that are very typical and who has no alarm symptoms together with normal biochemistry, normal haematology, normal inflammatory markers and normal TTG antibodies probably does not need to be further investigated. However alarm symptoms such as unusual abdominal pain that is progressive, evidence of gastrointestinal bleeding or weight loss would trigger further investigations.
In the older patient (for example someone over 50) the development of gastrointestinal symptoms that might initially suggest the irritable bowel syndrome should be further investigated whether or not there are alarm symptoms present because of the greater likelihood of pathology in the older age group than in the younger age group. This might even be in the absence of abnormalities in the various investigations mentioned above. There are of course exceptions to every rule. The irritable bowel syndrome is usually a condition that waxes and wanes over time so that the patient with progressive and worsening symptoms over some months does need to be investigated at whatever age they present and whatever the results of the above investigations are found to be.