What other diseases or conditions mimic indigestion (dyspepsia)?
Exclusion of non-functional gastrointestinal disease
As always, a detailed history from the patient and a physical examination frequently will suggest the cause of dyspepsia. Routine screening blood tests often are performed looking for clues to unsuspected diseases. Examinations of stool also are a part of the evaluation since they may reveal infection, signs of inflammation, or blood and direct further diagnostic testing. Sensitive stool testing (antigen/antibody) for Giardia lamblia would be reasonable because this parasitic infection is common and can be acute or chronic. Some physicians do blood testing for celiac disease (sprue), but the value of doing this is unclear. (Moreover, if an EGD is planned, biopsies of the duodenum usually will make the diagnosis of celiac disease.) If bacterial overgrowth of the small intestine is being considered, breath hydrogen testing can be considered.
There are many tests to exclude non-functional gastrointestinal diseases. The primary issue, however, is to decide which tests are reasonable to perform. Since each case is individual, different tests may be reasonable for different patients. Nevertheless, certain basic tests are often performed to exclude non-functional gastrointestinal disease. These tests identify anatomic (structural) and histological (microscopic) diseases of the esophagus, stomach, and intestines.
Both X-rays and endoscopies can identify anatomic diseases. Only endoscopies, however, can diagnose histological diseases because biopsies (samples of tissue) can be taken during the procedure. The X-ray tests include:
- The esophagram and video-fluoroscopic swallowing study for examining the esophagus
- The upper gastrointestinal series for examining the stomach and duodenum
- The small bowel series for examining the small intestine
- The barium enema for examining the colon and terminal ileum.
- The computerized tomography (CT) scan for examining the small intestine
The endoscopic tests include:
- Upper gastrointestinal endoscopy (esophago-gastro-duodenoscopy or EGD) to examine the esophagus, stomach and duodenum
- Colonoscopy to examine the colon and terminal ileum
- Endoscopy also is available to examine the small intestine, but this type of endoscopy is complex, not widely available, and of unproven value in indigestion.
For examination of the small intestine, there is also a capsule containing a tiny camera and transmitter that can be swallowed (capsule endoscopy). As the capsule travels through the intestines, it transmits pictures of the inside of the intestines to an external recorder for later review. The capsule is not widely available and its value, particularly in indigestion, has not yet been proven.
Newer endoscopes, similar to those used for EGD and colonoscopy are available that allow the entire small intestine to be examined. Unlike the capsule, however, the endoscope has channels in it that allow instruments to be passed into the intestine to collect samples of tissue (biopsies) and to treat abnormal findings such as polyps.
X-rays are easier to perform and less costly than endoscopies. The skills necessary to perform gastrointestinal X-rays, however, are becoming rare among radiologists because they are doing them less often. Therefore, the quality of the X-rays often is not as high as it used to be, and, as a result, CT scans of the small intestine are replacing small intestinal X-rays. As noted previously, endoscopies have an advantage over X-rays since at the time of endoscopies, biopsies can be taken to diagnose or exclude histological diseases, something that X-rays cannot do.
Exclusion of acid-related gastrointestinal diseases
Because they are so common, the most important non-functional gastrointestinal diseases to exclude are acid-related diseases that cause inflammation and ulceration of the esophagus, stomach, and duodenum. Infection of the stomach with Helicobacter pylori, an infection that is closely associated with some acid-related diseases, is included in this group. It is not clear, however, how often Helicobacter pylori causes indigestion. Moreover, the only way of excluding this bacterium as a cause of indigestion in a particular patient is by eliminating the infection (if it is present) with appropriate antibiotics. If indigestion is substantially improved by eradication, it is likely that the bacterium was responsible. Helicobacter pylori infection also can be diagnosed (or excluded) by blood tests, biopsy of the stomach, urea breath test, or a stool test.
Endoscopy is a good way of diagnosing or excluding acid-related inflammation. If no signs of inflammation are present, acid-related diseases are unlikely. Nevertheless, many patients without signs of inflammation respond to potent and prolonged suppression of acid, suggesting that acid is causing their indigestion. Therefore, many physicians will use potent suppression of acid in indigestion as a means to both treat and diagnose. Thus, if indigestion improves substantially (more than 50% to 75%) with suppression of acid, they consider it likely that acid is responsible for the indigestion. For this purpose, it is important to use potent acid suppression with proton pump inhibitors (PPIs), such as:
Treatment often is given at higher than recommended doses for 12 weeks or more before a decision is made about the effect of treatment on the symptoms. (A short course for just a few days or weeks is not enough.) If the symptoms of indigestion do not improve, it even may be reasonable to check the amount of acid produced by the stomach (and also the reflux of acid into the esophagus) by 24 hour pH monitoring to be certain that the acid-suppressing drugs are effectively suppressing acid. (Up to 10% of patients are resistant to the effects of even the PPIs.)
Exclusion of non-gastrointestinal disease
Patients with indigestion often undergo abdominal ultrasonography (US), computerized tomography (CT or CAT scans), or magnetic resonance imaging (MRI). These tests are used primarily to diagnose non-intestinal diseases. (Although the tests also are capable of diagnosing intestinal diseases, their value for this purpose is limited. X-ray and endoscopy are better.) It is important to realize that US, CT, and MRI are powerful tests and may uncover abnormalities that are unrelated to indigestion. The most common example of this is the finding of gallstones that, in fact, are causing no symptoms. (At least up to 50% of gallstones cause no symptoms.) This can cause a problem if the gallstones are assumed to be causing the indigestion. Surgical removal of the gallbladder with its gallstones (cholecystectomy) is unlikely to relieve the indigestion. (Cholecystectomy would be expected to relieve only the characteristic symptoms that gallstones can cause.) Additional tests to exclude non-gastrointestinal diseases may be appropriate in certain specific situations, although certainly not in most patients.
Exclusion of psychiatric disease
The possibility of psychiatric (psychological or psychosomatic) illness often arises in patients with indigestion because the symptoms are subjective and no objective abnormalities can be identified. Psychiatric illness may complicate indigestion, but it is unclear if psychiatric illness can cause indigestion. If there is a possibility of psychiatric illness, a psychiatric evaluation is appropriate, and psychiatric treatment may improve (though probably not cure) the symptoms.