Type of test Other
Normal findings
< 50 dpm (if 14C is used)
< 3% (if 13C is used)
Test explanation and related physiology
This test is used to detect Helicobacter pylori infections. It is indicated in patients who have recurrent or chronic gastric or duodenal ulceration or inflammation. When the H. pylori infection is successfully treated, the ulcer or inflammation will usually heal.
There are several serologic and microscopic methods of detecting H. pylori. The UBT is the noninvasive test of choice for diagnosis of H. pylori infection. It is based on the capability of H. pylori to metabolize urea to CO2 because of the organism’s capability to produce a large amount of urease. In the breath test, car bon (13C)-labeled urea is administered orally. The urea is then absorbed through the gastric mucosa. If H. pylori is present, the urea will be converted to 13CO2 . The 13CO2 is then taken up by the capillaries in the stomach wall and delivered to the lungs, where it is exhaled. The labeled carbon can be measured by gas chromatography or a mass spectrometer.
This test has been simplified to the point that two breath samples collected before and 30 minutes after the ingestion of urea in a liquid form suffice to provide reliable diagnostic information. Labeling urea with 13C is becoming increasingly popular because it is a nonradioactive isotope of 14C and is innocuous. It can be safely used in children and women of childbearing age.
Interfering factors
• Dietary constituents with a natural abundance of 13C, such as maize, cane, and corn flour, can cause increased levels.
* Bismuth (Pepto-Bismol) or sucralfate (Carafate) will suppress mucosal uptake of the urea and interfere with test results.
* The concomitant use of a proton pump inhibitor, such as Prilosec, Nexium, Prevacid, or Protonix, will also inhibit urea absorption.
Procedure and patient care
Before
* Explain the procedure to the patient.
* Instruct the patient to abstain from oral intake for 6 hours before testing.
• If radioactive carbon (rare) is being used, be sure that female patients are not pregnant.
* When providing the isotopic urea to the patient, instruct the patient as to proper administration (per laboratory routine).
During
• Several minutes after the patient has swallowed the carbon dose, provide the patient with 2 oz of water.
• Breath samples are collected in any one of a number of gas collection devices depending on how and when the sample will be analyzed.
After
* Instruct the patient to resume medications and normal diet.
* If radioactive carbon was used, instruct the patient to drink plenty of fluids to facilitate excretion of the radioisotope.
Abnormal findings
- H. pylori infection
