indigestion a commonly used term which encompasses a wide variety of gastrointestinal symptoms, including abdominal pain, heartburn, acid regurgitation, belching, bloating, bad breath, and even excessive passage of flatus. Each of these symptoms may have one of many causes when present as an isolated symptom and indicator of a specific disease; or many of them may occur together and be indicative of one or more disorders. Doctors may discern from the detailed history of the symptoms of ‘indigestion’ whether they are likely to represent a disorder of either the upper or the lower gastrointestinal tract.

The term indigestion however, is most often used to describe the symptom consortium often referred to as ‘dyspepsia’ — commonly defined as upper abdominal or epigastric pain which may or may not be related to eating. Associated symptoms may include heartburn, upper abdominal bloating, or belching. This is an extremely common condition occurring at one time or another in 25% of the adult population. Dyspepsia may be categorized as ‘organic dyspepsia’, when there is a clearly definable cause and disease entity, or as ‘functional dyspepsia’ when the pathophysiology has not been defined.

Organic dyspepsia

Common causes include chronic peptic ulcer, gastro–oesophageal reflux with or without oesophagitis, symptomatic gallstones, chronic pancreatitis; and intra-abdominal malignancy. Rarer causes include metabolic disorders, such as the uraemia of renal failure and hypercalcaemia, and conditions such as diabetes mellitus which disturb the function of the autonomic nervous system and hence impair gastric emptying.

Functional dyspepsia

Many now regard this as part of a wider spectrum of functional abdominal disorders which includes irritable bowel syndrome. In many instances the symptom pattern resembles that of an organic dyspepsia, although ‘alarm’ symptoms and signs such as weight loss, gastrointestinal bleeding, enlarged lymph glands, or an abdominal mass are absent. The cause of functional dyspepsia has not been clearly defined but is thought to relate to disturbances of motor function of the upper gastrointestinal tract, possibly associated with abnormalities of visceral sensation. Psychosocial factors such as stress, life events, and disturbance of affect are thought by some to be permissive for symptom production, even though they may not be the primary cause of the problem.

People under middle age who have no ‘alarm’ symptoms are not routinely investigated and are likely to be offered symptomatic treatment, with a variety of approaches including dietary modification, antacids, cognitive therapy, and possibly anti-depressant medication when appropriate. For those with symptoms that suggest the presence of organic disease, and for older people in whom such disease is in any case more likely, further investigation is required, such as upper gastrointestinal endoscopy, abdominal ultrasound scan; and possibly abdominal CT scan. Specific therapy can then be directed towards the identified cause.

Michael Farthing, and Anne Ballinger

See also alimentary tract.