Urea Breath Test
(UBT)
Medical Author: Jay W. Marks,
MD
Medical Editor: William C. Shiel, Jr., MD, FACP, FACR
What is the urea breath test?
The urea breath test (UBT) is a test for diagnosing the
presence of a bacterium, Helicobacter pylori (H. pylori) in the stomach.
H.
pylori causes inflammation, ulcers, and atrophy of the stomach. The test also may be used to
demonstrate that H. pylori has been eliminated by treatment with antibiotics.
What is the basis of this test?
The urea breath test is based on the ability of H. pylori to break down urea,
a chemical made up of nitrogen and carbon, into carbon dioxide which then is
absorbed from the stomach and eliminated in the breath. (Urea normally is
produced by the body from excess or "waste" nitrogen-containing chemicals and
then eliminated in the urine.)
How is this breath test done?
For the test, patients swallow a capsule containing urea made from an isotope of carbon.
(Isotopes of carbon occur in minuscule amounts in nature, and can be measured
with special testing machines.) If H. pylori is present in the stomach, the urea
is broken up and turned into carbon dioxide. The carbon dioxide is absorbed
across the lining of the stomach and into the blood. It then travels in the
blood to the lungs where it is excreted in the breath. Samples of exhaled breath
are collected, and the isotopic carbon in the exhaled carbon dioxide is
measured.
How are the results of the urea breath test interpreted?
If the isotope is detected in the breath, it means that H. pylori is present
in the stomach. If the isotope is not found, H. pylori is not present. When the
H. pylori is effectively treated (eradicated) by antibiotics, the test changes
from positive (isotope present) to negative (isotope absent).
Are there any risks or complications of the urea breath test?
There are no risks or complications of the urea breath test.
Last Editorial Review: 2/20/2009
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