Urea Breath Test for H.Pylori (Helicobacter Pylori)
- Two breath samples.
Purpose of the test (Indications)
- This test is used to detect Helicobacter Pylori infection.
- Advised in patients with recurrent:
- Chronic gastritis.
- Duodenal ulceration.
- Duodenal inflammatory process.
- Helicobacter pylori (H.pylori) is a gram-negative bacillus. This was known as Campylobacter pylori.
- Urea formation is summarized as follows.
- Urea formation takes place by the proteolysis of protein and the main site is the liver.
- H.pylori inhabit the mucous of the gastric mucosa.
- These bacteria are found in the mucus of the gastric mucosa.
- These bacteria cause damage to mucosa where HCL leads to ulcer formation.
- This is also considered as carcinogenic (class 1 gastric carcinogen).
- The colonies of H.Pylori are seen in:
- Duodenal ulcer = 90 to 95% .
- Gastric ulcer = 60 to 70%.
- gastric cancers = 20 to 25%.
- Around 10% of the young healthy people <30 years of age have the colonies of H.pylori.
- Gastric colonization by the H.pylori increases with age.
- Most of these patients remain asymptomatic and never develop an ulcer.
- This is a risk factor for the:
- Gastric ulcer.
- Chronic gastritis.
- Duodenal Ulcer.
- Ulcerative esophagitis.
The principle of Urea Breath test:
- H.pylori converts urea into CO2 due to the presence of the urease enzyme.
- Give orally radiolabelled urea (containing nonradioactive isotope 13C).
- In gastric mucosa, if H.Pylori present then it will convert urea into CO2 (13C).
- This CO2 (13C) labeled passes through blood and goes to the lung.
- Now measure CO2 (13C) by:
- Gas chromatography.
- Mass spectrometer.
- Procedure Two breath samples.
- First, take a sample before giving the isotope-labeled (13C) urea.
- Second after 30 minutes of a dose of isotope-labeled (13C) urea.
- Specificity and sensitivity are 95% and the test is cheap to diagnose in comparison to invasive procedures.
- Breath test (Source 4)
- <50 DPM for H. pylori.
- 50 to 199 DPM for H. pylori
- >200 DPM positive for H. pylori.
- < 3 % .
- A positive test means H. Pylori infection.
- Source 1
- The presence of IgG and IgA antibodies are seen in 81 to 100% of the patient with gastritis.
- But in only 25% of the patients without histological evidence of H. pylori.
- The testing of IgM is not helpful.
- You can get a false negative test if the patient uses antacids within a week prior to the test.
- The patient should not use any antibiotics and bismuth for one month.
- No proton pump inhibitors and sucralfate for two weeks before the test.
- The patient should be at rest during the collection of breath.
Diagnosis of H. pylori:
It can be diagnosed by the following tests>
- Positive breath test.
- Presence of specific antibody. Sensitivity is 94% and specificity is 78%.
- Positive culture.
- A positive biopsy is done by endoscopy. Sensitivity is 93% and specificity is 99%.
- The stool is examined for the H. pylori antigen.