Stomach ulcer diagnosis: How the H. pylori urea breath test works

 Key takeaways:

• H. pylori is notorious for causing stomach ulcers and other changes in cells that line the upper GIT.
• There are different types of tests for diagnosing stomach ulcers, including the H. pylori urea breath test.
• The H. pylori urea breath test works by detecting the presence of urease an enzyme produced by the H. pylori bacteria after the enzyme breaks down urea used for the test into ammonia and carbon dioxide.

The H. pylori urea breath test is a good way to find out if someone has an H. pylori infection in their stomach. H. pylori is a bacteria that causes some acid-related disorders like stomach ulcers.

The test has no side effects and is safe for diagnosing medical conditions like stomach ulcers. Aside from testing for stomach ulcers, the H. pylori urea breath test can also be used to ascertain whether your ulcer treatment was effective.

Your doctor will let you know if you need to do the urea breath test. You will also be given some instructions on how to prepare for the test before the procedure.

In this article, we will discuss all you need to know about the H. pylori urea breath test; how it works; how to prepare for the test; the procedure for the test; and the cost.

 What is H. pylori?

Helicobacter pylori, called H. pylori for short, is a bacteria found in the digestive tract which attacks the stomach lining, duodenum, and the first part of the small intestine. "Helico" means spiral, meaning that the bacteria has a spiral shape. They adapt easily to the acidic environment in the stomach.

The Helicobacter pylori bacteria can change the environment of the stomach and make it less acidic so that it can grow and spread. When the bacteria get into the stomach, it is often harmless initially, until later when they start causing some problems like stomach ulcers. However, not everyone who is infected by the bacteria develops a stomach ulcer.

The spiral shape of the bacteria allows it to easily enter the stomach and attack the stomach lining. It can be transmitted via direct contact with the stool, saliva, or vomit of an infected person. It can also be transmitted through contaminated water or food.

 What is the H. pylori urea breath test?

The H. pylori urea breath test is a test used to determine the presence of H. pylori in the stomach.

The test can be carried out if your doctor wants to diagnose health conditions like stomach ulcers. Your doctor may also order the test if you have previously been diagnosed with an ulcer and there is a need to check for reoccurrence.

The H. pylori urea breath test is a simple and fast test that is basically used to:

• Detect the presence of H. pylori infection
• Test for an active infection
• Find out if an infection has been cured after treatment

 How does the H. pylori urea breath test work?

H. pylori produces urease, an enzyme that degrades urea into ammonia and carbon dioxide. Urease is not found in human cells but is found in pathogenic bacteria such as Helicobacter pylori. Therefore, a test that detects the enzyme often indicates the presence of H. pylori.

"The urea breath test is a chemical reaction-based test that is used to detect the presence of H. pylori bacteria infection in the stomach and upper intestines. The bacteria, H. pylori, produces an enzyme called urease that hydrolyzes or breaks down urea to ammonia and CO2," Ngwoke Ifeanyi, a medical laboratory scientist and M&E assistant at eHealth Africa, told SemicHealth.

"This is the chemical reaction and principle behind the test. However, in the urea breath test, a tagged urea capsule is used. The capsule is tagged with a safe radioactive isotope of carbon (carbon-14).

"So, when a patient with H. pylori ingests the urea capsule, the bacteria produce urease that breaks down the urea to ammonia, water, and carbon dioxide. The tagged carbon dioxide is absorbed rapidly and excreted through the lungs. The peak time is 15 minutes. The patient is asked to breathe into an airbag and the carbon dioxide level is measured," Ngwoke explained.

A device that detects carbon would be used to measure the amount of carbon you exhale into the bag. The amount of carbon dioxide in the bag will be measured against a baseline sample that was taken without the urea capsule. A higher-than-normal carbon dioxide level will indicate the presence of H. pylori.

 Who should take the H. pylori urea breath test?

The H. pylori urea breath test can be taken by adults and children over 6 years of age. If you have constant pain in your digestive tract or if you are noticing any of the following symptoms, your doctor might recommend a urea breath test:

• Bloating
• Unexplained weight loss
• Pain in your stomach that gets relieved when you take an antacid
• Feeling pain in your upper abdomen after meals or in between meals
• Vomiting
• Nausea

You should also take the H. pylori urea breath test if you have a previous history of ulcers, or if you want to confirm if your ulcer treatment worked perfectly.

 How to prepare for the H. pylori urea breath test

"The H. pylori urea breath test lasts for about 30–40 minutes, and there are a few preparatory instructions," Ngwoke said. The preparatory instructions may sound like this:

• Do not take antibiotics 4 weeks before your test.
• Keep taking your medications prior to the urea breath test unless your doctors ass you to stop.
• Do not eat or drink 6 hours before your test.
• Do not chew gum on the day you will run your test.
• 2 to 4 weeks before the test, you should stop taking the following medications, histamine blockers, bismuth subsalicylate, and proton pump inhibitors. This is because these drugs can cause a false negative result by reducing the activity of the urease enzyme.

Depending on the laboratory center, there could be changes to these instructions or more instructions to help prepare your body for the test. Adhere to the instructions your medical team gives you.

 Procedure for H. pylori urea breath test

During the actual test, you will need to exhale into two balloon-like airbags. You will exhale into the first airbag without taking any urea capsules. This is to measure the normal amount of carbon dioxide you exhale before taking the urea and will be used as a baseline for measuring the carbon dioxide amount after you have exhaled into the second airbag.

After this, you will be given the "tagged urea capsule—most times in a lemon-flavored juice for easy digestion. After about 15 minutes, you breathe again into the bag, and the new level of carbon dioxide is measured. At this point, the test is done," Ngwoke explained.

Here is a brief overview of how the H. pylori urea breath test is performed:

1. You will be asked to exhale into a balloon-like bag and the amount of carbon dioxide collected will be measured.
2. You will be given a small amount of lemon-flavored solution that contains urea or a urea capsule to ingest.
3. You will breathe into the balloon bag again after 15 minutes and the carbon dioxide will be measured again.

 How to interpret the H. pylori urea breath test result

In the H. pylori test, the presence of H. pylori is confirmed after measuring the difference between the first and second tests.

"The result is usually calculated and interpreted by an electronic scintillator or measuring device. A significant change in the levels of carbon dioxide with the carbon isotope indicates a positive test," Ngwoke said.

Here is how clinicians interpret the H. pylori urea breath test result:

• Positive result: A positive result outcome means that you have H pylori in your stomach. An H. pylori urea breath test result is said to be positive when the carbon dioxide in the second sample (exhaled after taking the urea sample) is higher than the one gotten from the first sample.
• Negative result: A negative test result shows you do not have H pylori in your stomach. When the results are negative, it means that there was no significant difference between the amount of carbon dioxide in your first and second samples.

 Cost of H. pylori urea breath test

Not all tests are common in Nigeria. Most laboratories prefer to use other tests, such as antigen-antibody test kits or endoscopy followed by stained biopsy examination, to find out if someone has H. pylori infection.

"The H. pylori urea breath test is uncommon and almost not used in Nigeria. Therefore, there are no popular cost ranges in places where it is done, if there is any," Ngwoke explained.

However, if you are going for other urea breath test alternatives, "the antigen-antibody test kits cost around N1,000-N5,000 depending on the laboratory facility, while the endoscopy with biopsy could go for as much as N40,000-N75,000 depending on the medical laboratory," Ngwoke added.

 Wrap up

The H. pylori urea breath test is one method used to diagnose conditions like stomach ulcers. The test works by using urea breath tests to find out whether a person is infected with the H. pylori bacteria. The test doesn't take much time—30–40 minutes. However, it is not common in Nigeria.

If your doctor thinks you have stomach ulcers, they may suggest that you take other tests, like the antigen-antibody test or the endoscopy test with biopsy. Speak to your healthcare provider regarding how to prepare for any of the tests and what to expect during the tests.