Last updated on June 2nd, 2021
Urea breath test (UBT) is a qualitative and non-invasive rapid test for the diagnosis of Helicobacter pylori (the major cause of gastric and duodenal ulcers) infections. Helicobacter pylori is a fastidious bacterium that is known to be a potent producer of the urease enzyme. Urease breaks urea in the stomach down into ammonia and carbon dioxide which raises the pH of the environment surrounding the organism and allows it to survive in the acidic environment of the stomach.
Find information about “Urease test and urease positive microorganisms HERE”.
Urea breath test is highly accurate (positive predictive value 100%, negative predictive value 98%) and extremely reliable for pretreatment diagnosis and post-treatment evaluation of “proof-of-cure”.
Patients swallow test capsule which contains urea tagged with radioactive carbon14 i.e. (14C-urea). If the patient is infected with H. pylori, the test urea will be broken down and a lot of 14CO2 will be produced. This 14CO2 is quickly absorbed, moves from the blood to the lungs, and is exhaled in the breath which is detected by the instrument in the breath of the patients.
Following ingestion of the capsule by a patient infected with H.pylori, 14CO2 excretion in the breath peaks between 15-20 minutes and declines thereafter. 14C-urea that is not hydrolyzed by H.pylori is excreted in the urine. If the patient is not infected with H. pylori, the urea will not degrade, and so hardly any 14CO2 will be exhaled.
The detection in the breath differs among manufactures. Some manufactures have come up with an easier detection method. Currently, our laboratory uses the UBT test device of Headway. The working principle of their device is shown in this image.
Uses of Urea Breath Test (UBT)
- To find active cases of pylori infections:
- To determine if a patient is actively infected with pylori both pre and post-therapy. Positive C14 Urea breath test only tells that the patient is actively infected with H.pylori.
- Urea breathe test may prevent patients with positive pylori serology (but no active infection) being unnecessarily treated with broad-spectrum antibiotics. C14 Urea breath test comes positive only in the patients who are actively infected with H.pylori. H.pylori serology cannot reliably distinguish between past or present infection.
- Monitoring the efficacy of the treatment: The C14 Urea breath test is generally accepted as the non-invasive test of choice for determining whether or not eradication of pylori has been achieved. Even after successful treatment, serology may remain positive for 6 months or longer, so H.pylori serology will not reliably tell whether or not eradication of the organism has been achieved after the treatment. A C14 test may demonstrate eradication just 4-6 weeks post-treatment.
Test Instructions and Test Procedures:
Physician should provide appropriate information to patients prior to testing. This includes restrictions on medicine (you have to cease all forms of antibiotics including Bismuth, 12 weeks prior to the test, please consult with your GP/physician) and the requirement to fast (no food or water) for a minimum of four hours (recommended 6 hours) prior to testing.
- Swallow one urea [14C] capsule with water on an empty stomach or four hours after eating (food or drinks).
- Sit calmly for 10-15 minutes.
- Unpack and take out the mouthpiece and collection card body.
- Connect the mouthpiece to the front end of the collection card body.
- Blow reposefully through the mouthpiece, as long as possible.
- You can exchange breath during blowing. DO NOT inhale from the mouthpiece!
- Blow continuously for 3-5 minutes until the indicator of the collection card turns from orange to yellow.
- Discard the mouthpiece into the dustbin. Handover the collection card body to the operator for analysis and wait for the test results.
(Note: This sample collection process is based on the use of Helicobacter pylori test system and may vary according to the use of detection system for radiolabelled carbon dioxide.)
Detection of radiolabelled carbon dioxide in the breath
- Some test utilizes a liquid scintillation counter for the measurement of 14CO2 in breath samples.
In our settings, we use Helicobacter pylori test system for the detection of 14CO2 in breath samples.
The test is considered safe in pregnancy or in childhood. An issue that is frequently raised is the dose of radiation. The dose of radiation received during C14 breath testing is equivalent to only three microsieverts (this is one-tenth the dose of a plain Chest-X ray and equivalent to half the normal daily background exposure to radiation for everyday living).
References and Further Reading: