Urea breath test

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Urea breath test
Urea breath test kit.jpg
Urea breath test, UBT-KIT for "Helicobacter pylori", (Ubit Tab; left)
ICD-9-CM 89.39

The urea breath test is a rapid diagnostic procedure used to identify infections by Helicobacter pylori , a spiral bacterium implicated in gastritis, gastric ulcer, and peptic ulcer disease. It is based upon the ability of H. pylori to convert urea to ammonia and carbon dioxide. Urea breath tests are recommended in leading society guidelines as a preferred non-invasive choice for detecting H. pylori before and after treatment. [1] [2]

Contents

Principles and mechanism

Patients swallow urea labelled with an uncommon isotope, either radioactive carbon-14 (nowadays preferred in many countries) or non-radioactive carbon-13. In the subsequent 10–30 minutes, the detection of isotope-labelled carbon dioxide in exhaled breath indicates that the urea was split; this indicates that urease (the enzyme that H. pylori uses to metabolize urea to produce ammonia) is present in the stomach, and hence that H. pylori bacteria are present.

For the two different forms of urea, different instrumentation is required. Carbon-14 is normally measured by scintillation, whereas carbon-13 can be detected by isotope ratio mass spectrometry or simpler by nondispersive infrared (NDIR) spectrometry. For each of these methods, a baseline breath sample is required before taking the isotope-labeled urea, for comparison with the post-urea sample, with a 15- to 30-minute duration between them. Samples may be sent to a reference laboratory for analysis. Alternatively, NDIR spectrometry can be performed by a table-top instrument as an office-based test, and results are provided immediately within minutes. [3] [4] [5]

The difference between the pre- and post urea measurements is used to determine infection. This value is compared to a cut-off value. Results below the value are assumed to be negative, those above positive. The cut-off value itself is determined by comparing the results of patients with two or more different detection methods. The value is chosen that gives the best combination of sensitivity and specificity. Both carbon-14 and carbon-13 urea breath tests have high sensitivity and specificity, though the carbon-13 test is preferred in certain populations due to its non-radioactive nature. [6]

The test measures active H. pylori infection. If antibiotics are depressing the amount of H. pylori present, or the stomach conditions are less acidic than normal, the amount of urease present will be lessened.

Accordingly, the test should only be performed 14 days after stopping acid reducing medication (proton pump inhibitors, PPI) or 28 days after stopping antibiotic treatment. Some clinicians believe that a reservoir of H. pylori in dental plaque can affect the result. [7]

The test is especially done accompanying an eradication therapy by antibiotics (to avoid overdosing) or to check the success of an ulcer operation. In both cases, immunological tests can give false positive results. [1] [2]

See also

Related Research Articles

Peptic ulcer disease is a break in the inner lining of the stomach, the first part of the small intestine, or sometimes the lower esophagus. An ulcer in the stomach is called a gastric ulcer, while one in the first part of the intestines is a duodenal ulcer. The most common symptoms of a duodenal ulcer are waking at night with upper abdominal pain, and upper abdominal pain that improves with eating. With a gastric ulcer, the pain may worsen with eating. The pain is often described as a burning or dull ache. Other symptoms include belching, vomiting, weight loss, or poor appetite. About a third of older people with peptic ulcers have no symptoms. Complications may include bleeding, perforation, and blockage of the stomach. Bleeding occurs in as many as 15% of cases.

<span class="mw-page-title-main">Carbon-14</span> Isotope of carbon

Carbon-14, C-14, 14
C
or radiocarbon, is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons. Its presence in organic materials is the basis of the radiocarbon dating method pioneered by Willard Libby and colleagues (1949) to date archaeological, geological and hydrogeological samples. Carbon-14 was discovered on February 27, 1940, by Martin Kamen and Sam Ruben at the University of California Radiation Laboratory in Berkeley, California. Its existence had been suggested by Franz Kurie in 1934.

<span class="mw-page-title-main">Urease</span> Multiprotein Nickel-containing complex which hydrolyses urea

Ureases, functionally, belong to the superfamily of amidohydrolases and phosphotriesterases. Ureases are found in numerous bacteria, fungi, algae, plants, and some invertebrates, as well as in soils, as a soil enzyme. They are nickel-containing metalloenzymes of high molecular weight.

<i>Helicobacter pylori</i> Species of bacteria

Helicobacter pylori, previously known as Campylobacter pylori, is a gram-negative, flagellated, helical bacterium. Mutants can have a rod or curved rod shape, and these are less effective. Its helical body is thought to have evolved in order to penetrate the mucous lining of the stomach, helped by its flagella, and thereby establish infection. The bacterium was first identified as the causal agent of gastric ulcers in 1983 by the Australian doctors Barry Marshall and Robin Warren.

<i>Helicobacter</i> Genus of bacteria

Helicobacter is a genus of gram-negative bacteria possessing a characteristic helical shape. They were initially considered to be members of the genus Campylobacter, but in 1989, Goodwin et al. published sufficient reasons to justify the new genus name Helicobacter. The genus Helicobacter contains about 35 species.

<span class="mw-page-title-main">Barry Marshall</span> Australian physician (born 1951)

Barry James Marshall is an Australian physician, Nobel Prize Laureate in Physiology or Medicine, Professor of Clinical Microbiology and Co-Director of the Marshall Centre at the University of Western Australia. Marshall and Robin Warren showed that the bacterium Helicobacter pylori plays a major role in causing many peptic ulcers, challenging decades of medical doctrine holding that ulcers were caused primarily by stress, spicy foods, and too much acid. This discovery has allowed for a breakthrough in understanding a causative link between Helicobacter pylori infection and stomach cancer.

A radioactive tracer, radiotracer, or radioactive label is a synthetic derivative of a natural compound in which one or more atoms have been replaced by a radionuclide. By virtue of its radioactive decay, it can be used to explore the mechanism of chemical reactions by tracing the path that the radioisotope follows from reactants to products. Radiolabeling or radiotracing is thus the radioactive form of isotopic labeling. In biological contexts, experiments that use radioisotope tracers are sometimes called radioisotope feeding experiments.

<span class="mw-page-title-main">Gastritis</span> Stomach disease that is an inflammation of the lining of the stomach

Gastritis is inflammation of the lining of the stomach. It may occur as a short episode or may be of a long duration. There may be no symptoms but, when symptoms are present, the most common is upper abdominal pain. Other possible symptoms include nausea and vomiting, bloating, loss of appetite and heartburn. Complications may include stomach bleeding, stomach ulcers, and stomach tumors. When due to autoimmune problems, low red blood cells due to not enough vitamin B12 may occur, a condition known as pernicious anemia.

<span class="mw-page-title-main">Achlorhydria</span> Medical condition

Achlorhydria and hypochlorhydria refer to states where the production of hydrochloric acid in gastric secretions of the stomach and other digestive organs is absent or low, respectively. It is associated with various other medical problems.

Carbon-13 (13C) is a natural, stable isotope of carbon with a nucleus containing six protons and seven neutrons. As one of the environmental isotopes, it makes up about 1.1% of all natural carbon on Earth.

<span class="mw-page-title-main">Robin Warren</span> Australian pathologist

John Robin Warren is an Australian pathologist, Nobel Laureate and researcher who is credited with the 1979 re-discovery of the bacterium Helicobacter pylori, together with Barry Marshall. The duo proved to the medical community that the bacterium Helicobacter pylori is the cause of most peptic ulcers.

Isotopic labeling is a technique used to track the passage of an isotope through chemical reaction, metabolic pathway, or a biological cell. The reactant is 'labeled' by replacing one or more specific atoms with their isotopes. The reactant is then allowed to undergo the reaction. The position of the isotopes in the products is measured to determine the sequence the isotopic atom followed in the reaction or the cell's metabolic pathway. The nuclides used in isotopic labeling may be stable nuclides or radionuclides. In the latter case, the labeling is called radiolabeling.

<span class="mw-page-title-main">Rapid urease test</span> Test for Heliobacter pylori infection

Rapid urease test, also known as the CLO test, is a rapid diagnostic test for diagnosis of Helicobacter pylori. The basis of the test is the ability of H. pylori to secrete the urease enzyme, which catalyzes the conversion of urea to ammonia and carbon dioxide.

Timeline of peptic ulcer disease and <i>Helicobacter pylori</i>

This is a timeline of the events relating to the discovery that peptic ulcer disease and some cancers are caused by H. pylori. In 2005, Barry Marshall and Robin Warren were awarded the Nobel Prize in Physiology or Medicine for their discovery that peptic ulcer disease (PUD) was primarily caused by Helicobacter pylori, a bacterium with affinity for acidic environments, such as the stomach. As a result, PUD that is associated with H. pylori is currently treated with antibiotics used to eradicate the infection. For decades prior to their discovery, it was widely believed that PUD was caused by excess acid in the stomach. During this time, acid control was the primary method of treatment for PUD, to only partial success. Among other effects, it is now known that acid suppression alters the stomach milieu to make it less amenable to H. pylori infection.

Helicobacter pylori eradication protocols is a standard name for all treatment protocols for peptic ulcers and gastritis in the presence of Helicobacter pylori infection. The primary goal of the treatment is not only temporary relief of symptoms but also total elimination of H. pylori infection. Patients with active duodenal or gastric ulcers and those with a prior ulcer history should be tested for H. pylori. Appropriate therapy should be given for eradication. Patients with MALT lymphoma should also be tested and treated for H. pylori since eradication of this infection can induce remission in many patients when the tumor is limited to the stomach. Several consensus conferences, including the Maastricht Consensus Report, recommend testing and treating several other groups of patients but there is limited evidence of benefit. This includes patients diagnosed with gastric adenocarcinoma, patients found to have atrophic gastritis or intestinal metaplasia, as well as first-degree relatives of patients with gastric adenocarcinoma since the relatives themselves are at increased risk of gastric cancer partly due to the intrafamilial transmission of H. pylori. To date, it remains controversial whether to test and treat all patients with functional dyspepsia, gastroesophageal reflux disease, or other non-GI disorders as well as asymptomatic individuals.

<span class="mw-page-title-main">Troxipide</span> Chemical compound

Troxipide is a drug used in the treatment of gastroesophageal reflux disease. Troxipide is a systemic non-antisecretory gastric cytoprotective agent with anti-ulcer, anti-inflammatory and mucus secreting properties irrespective of pH of stomach or duodenum. Troxipide is currently marketed in Japan (Aplace), China (Shuqi), South Korea (Defensa), and India (Troxip). It is used for the management of gastric ulcers, and amelioration of gastric mucosal lesions in acute gastritis and acute exacerbation of chronic gastritis.

Helicobacter felis is a bacterial species in the Helicobacteraceae family, Campylobacterales order, Helicobacter genus. This bacterium is Gram-negative, microaerophilic, urease-positive, and spiral-shaped. Its type strain is CS1T. It can be pathogenic.

Helicobacter salomonis is a species within the Helicobacter genus of Gram-negative bacteria. Helicobacter pylori is by far the best known Helicobacter species primarily because humans infected with it may develop gastrointestinal tract diseases such as stomach inflammation, stomach ulcers, duodenal ulcers, stomach cancers of the nonlymphoma type, and various subtypes of extranodal marginal zone lymphomass, e.g. those of the stomach, small intestines, large intestines, and rectumn. H. pylori is also associated with the development of bile duct cancer and has been associated with a wide range of other diseases, although its role in the development of many of these other diseases requires further study. Humans infected with H. salomonis may develop some of the same gastrointestinal diseases viz., stomach inflammation, stomach ulcers, duodenal ulcers, stomach cancers that are not lymphomas, and extranodal marginal B cell lymphomas of the stomach. Other non-H. pylori Helicobacter species that are known to be associated with these gastrointestinal diseases are Helicobacter bizzozeronii, Helicobacter suis, Helicobacter felis, and Helicobacter heilmannii s.s. Because of their disease associations, these four Helicobacter species plus H. salomonis are often group together and termed Helicobacter heilmannii sensu lato.

Helicobacter suis is a species within the Helicobacter genus of Gram-negative bacteria. Helicobacter pylori is by far the best known Helicobacter species, primarily because humans infected with it may develop gastrointestinal tract diseases such as stomach inflammation, stomach ulcers, duodenal ulcers, stomach cancers of the nonlymphoma type, and various subtypes of extranodal marginal zone lymphomass, e.g. those of the stomach, small intestines, large intestines, and rectumn. H. pylori is also associated with the development of bile duct cancer and has been associated with a wide range of other diseases although its role in the development of many of these other diseases requires further study. Humans infected with H. suis may develop some of the same gastrointestinal diseases - stomach inflammation, stomach ulcers, duodenal ulcers, stomach cancers that are not lymphomas, and extranodal marginal B cell lymphomas of the stomach. Other non-H. pylori Helicobacter species that are known to be associated with these gastrointestinal diseases are Helicobacter bizzozeronii, Helicobacter salomonis, Helicobacter felis, and Helicobacter heilmannii s.s. Because of their disease associations, these four Helicobacter species plus H. suis are often group together and termed Helicobacter heilmannii sensu lato.

Helicobacter cetorum is a Gram-negative, microaerophilic, spiral (helical) bacterium that is usually found in the stomachs of whales and dolphins. Based on 16S rRNA sequencing, its genome is very similar to that of Helicobacter pylori in that it can cause gastric disease in these animals. Originally isolated among Atlantic white-sided dolphins and Beluga whales in 2000, H. cetorum has been associated with hemorrhages throughout its entire gastrointestinal tract, but its role has not yet been discovered. Prior to the discovery of H. cetorum, there have not been any other Helicobacter species reported in dolphins.

References

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