PYtest Kit (C-Urea Breath Test) | PYtest [Avent, Inc.] | BioPortfolio

12:34 EST 27th January 2019 | BioPortfolio

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PYtest (C-Urea Breath Test) is a qualitative and non-invasive method for the diagnosis of Helicobacter pylori (H.pylori). To detect H.pylori, C-urea supplied in a capsule is swallowed by the patient. If gastric urease from H.pylori is present, Urea is split to form CO and NH. Ten minutes after the patient ingests the capsule, a breath sample is collected into a balloon. The breath sample is later transferred to collection fluid to trap the labeled CO. The liquid sample is then analyzed in a liquid scintillation counter.

The PYtest Kit (C-Urea Breath Test) is designed for use with the PYtest capsule, a gelatin capsule for oral administration containing 1 µCi of C labeled urea. The urea is adsorbed on sugar spheres and colored yellow with fluorescein.

Structural Formula (C-urea): NH CONH

Radiation emission: beta-emission, 49 keV 156 keV no other emissions

External emission: No external radiation hazard. Low-energy beta emissions only. Maximum range of 0.3 mm in water.

Radiological Half-life: 5730 years

Maximum effective dose equivalent (EDE) : 0.3 mrem/µCi

The urease enzyme is not present in mammalian cells, so the presence of urease in the stomach is evidence that bacteria are present. The presence of urease is not specific for H.pylori, but other bacteria are not usually found in the stomach. The principle of the breath test is shown in Figure 1.

Figure 1: Principle of Breath Test

To detect H.pylori, urea labeled with C is swallowed by the patient. If gastric urease from H.pylori is present, urea is split to form CO and NH at the interface between the gastric epithelium and lumen and CO is absorbed into the blood and exhaled in the breath.

Following ingestion of the capsule by a patient with H.pylori, CO excretion in the breath peaks between 10 and 15 minutes and declines thereafter with a biological half-life of about 15 minutes. C-urea that is not hydrolyzed by H.pylori is excreted in the urine with a half-life of approximately 12 hours. About 10% of the C remains in the body at 72 hours and is gradually excreted with a biological half-life of 40 days.

Two studies were performed. In both studies, patients with gastrointestinal symptoms underwent the breath test and an endoscopy. During the endoscopy, biopsy samples were taken from the antral gastric mucosa for histological analysis (2 samples, Giemsa stain) and rapid urease test (1 sample, CLOtest). Breath samples were mailed to the TRI-MED lab where they were read in a liquid scintillation counter.

Results were reported as disintegrations per minute (DPM). Analysis for accuracy used the ten minute breath sample. A breath sample DPM <50 was defined as a negative result. DPM ≥200 was defined as a positive result. DPM in the range of 50 -199 was classified as indeterminate.

Of 186 patients who had histopathology and CLOtest (80 men, 106 women), 53 were infected with H.pylori as determined by agreement between histology and CLOtest. The study results are summarized below:

Table 1: Study #1 (n=186, Indeterminate results included)
Histology and CLOtest
H.pylori Positive Negative Total
Notes: PYtest at 10 min. was compared to the gold standard of biopsy results in which histology and CLOtest concurred. Patients who did not have both biopsy tests performed, or in whom the tests differed, were excluded from analysis. There was no statistical difference in test accuracy based on gender of patient.
ppv = positive predictive value (true positive divided by total
          PYtest positive)
npv = negative predictive value (true negative divided by total
          PYtest negative)
PYtest Positive 51 8     59   ppv. 86%
(DPM Indeterminate 1   8     9    
10m.) Negative 1   117 118 npv. 99%
Total 53 133 186

Breath tests were performed on 436 outpatients attending gastroenterology practices at sites in the United States. Seventy-six patients (40 men, 36 women) who had histology and CLOtest were evaluated. The results are summarized below:

Table 2: Study #2 (n=76, Indeterminate results included)
Histology and CLOtest
H.pylori Positive Negative Total
Notes: PYtest at 10 min. was compared to the gold standard of biopsy results in which histology and CLOtest concurred. Patients who did not have both biopsy tests performed, or in whom the tests differed, were excluded from analysis. There was no statistical difference in test accuracy based on gender of patient.
ppv = positive predictive value (true positive divided by total
          PYtest positive)
npv = negative predictive value (true negative divided by total
         PYtest negative)
PYtest Positive 22 0   22 ppv. 100%
(DPM Indeterminate 4   2   6  
10m.) Negative 1   47 48 npv. 98%
Total 27 49 76

PYtest (C-Urea Breath Test) is indicated for use in the detection of gastric urease as an aid in the diagnosis of H.pylori infection in the human stomach. The test utilizes a liquid scintillation counter for the measurement of CO in breath samples.



After the patient ingests the C-urea capsule, the sample collected for test purposes is for in vitro diagnostic use only.

A false positive test could occur in patients who have achlorhydria. Very rarely, a false positive test may occur due to urease associated with Helicobacters other than H.pylori (i.e. Helicobacter heilmanni).

Persons concerned about very low doses of radioactivity may postpone the test or may decide to use an alternative means of diagnosis. The test produces radiation exposure equal to 24 hours of normal background. In animal experiments, such low doses of radiation do not carry measurable risk.

Preclinical studies were not conducted on C-urea. The estimated dose equivalent received from a single administration of PYtest (1µCi C) is about 0.3 mrem.

It is necessary for the patient to fast for 6 hours before the test. The patient should also be off antibiotics and bismuth for 1 month, and proton pump inhibitors and sucralfate for 2 weeks prior to the test. Instruct the patient not to handle the capsule directly as this may interfere with the test result. The capsule should be swallowed intact. Do not chew the capsule.

No studies have been conducted with C-urea to evaluate its potential for carcinogenicity, impairment of fertility, or mutagenicity.

Antibiotics, proton pump inhibitors, sucralfate, and bismuth preparations are known to suppress H.pylori. Ingestion of antibiotics or bismuth within 4 weeks and proton pump inhibitors or sucralfate within 2 weeks prior to performing the test may give false negative results.

Animal reproduction studies have not been conducted with PYtest (C-urea). It is also not known whether PYtest can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. PYtest should be given to a pregnant woman only if clearly needed.

It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when PYtest is administered to a nursing woman.

Clinical studies in children have not been conducted. However, PYtest is expected to work the same in children as in adults. While the dose (1 capsule) does not need to be adjusted, the child must be able to swallow the intact capsule and blow into a straw.

No adverse reactions were reported in clinical trials.

Risk from radiation is negligible even with a 1000 capsule overdose (0.3 rem). If overdose occurs, the patient may drink one glass of water (150 mL) every hour to hasten excretion of the isotope. Maximum excretion of Urea is achieved at a urine output of ≥2.0 mL/min.

As shown in Figure 2, the PYtest Kit contains:

Figure 2: PYtest Kit

One PYtest capsule.

Table 3: Breath Sample Collection by Balloon
Before the test Label balloon and fill in breath test report form. Check that all materials are present.
Minus 1 Open the package containing the 14C-urea capsule minute and tip the capsule into the empty 30 mL cup. Do not handle the capsule directly. Hand the cup to the patient. Fill the second cup with 20 mL lukewarm water.
0 minute Ask the patient to tip the capsule directly into his/her mouth, then swallow it with the 20 mL of lukewarm water. Start the stopwatch when the patient swallows the capsule. Discard waste (e.g., capsule packaging, used straws) according to your facility's regulations.
3 minutes Ask the patient to drink another 20 mL of lukewarm water (in case the capsule may have lodged in the esophagus and not yet reached the gastric mucosa).
10 minutes Push a drinking straw into the neck of the balloon. Ask the patient to hold his/her breath for 5-10 seconds, then blow up a balloon with a slow breath through the straw, filling the balloon completely. Tie the neck of the balloon into a tight knot. Check that the balloon label and the breath test report form are completed correctly.
After the test Place the filled balloon and breath test report in the box and forward to Kimberly-Clark for analysis.

A minimum of 1 mM of CO is required to perform analysis of a breath sample. The amount of breath required to provide 1 mM of CO varies depending on the amount of CO the patient is producing. Since a full balloon typically contains at least 1 mM of CO, the balloon should be completely filled.

The indeterminate result should be evaluated by repeating the PYtest or using an alternative diagnostic method. If repeat breath testing is undertaken, careful history to exclude confounding factors should be obtained. If confounding factors are present, wait an appropriate time (refer to Table 4) before repeating the PYtest.

The cutoff point of 50 DPM was determined to be the mean + 3SD of results obtained in patients who did not have H.pylori.

DPM = Disintegrations per minute

Interpretation of results (10 minute sample)
     <50 DPM Negative for H.pylori
     50-199 DPM Indeterminate for H.pylori
     ≥200 DPM Positive for H.pylori
Table 4: Factors which might cause sub-optimal breath test results
Factor Result Comment
Recent antibiotic or bismuth (Pepto-Bismol, etc.) false neg. Relapse of partially treated Hp may take 1-4 weeks.
Omeprazole (or other proton pump inhibitors) false neg. These agents suppress Hp in 40% of patients. Discontinue for at least 2 weeks before performing the PYtest.
Resective gastric surgery false neg. Isotope may empty rapidly from the stomach.
Resective gastric surgery false pos. Patient may be achlorhydric and have bacterial overgrowth (non-Hp urease).
Food in stomach (also bezoar, gastroparesis) unknown Isotope may not come into contact with gastric mucosa. Patient may be achlorhydric and/or have bacterial overgrowth (non-Hp urease).

As shown in Figure 3 approximately 30% of patients tested will be positive for H.pylori.

Figure 3: Histogram showing DPM distribution for the PYtest.

Note: DPM groupings were calculated on a logarithmic scale. Empty DPM groupings were not included. Chart includes all patients from Studies 1 and 2.

Frequency of DPM group includes samples with DPM < Group Name.

     DPM = Disintegrations per minute

     Gold Standard = Agreement between histology and CLOtest

If the capsule is damaged or appears abnormal in any way, it may give inaccurate results.

PYtest Kit (C-Urea Breath Test) is supplied as a kit containing a PYtest Capsule, a clear gelatin capsule containing 1µCi of C-urea and breath collection equipment.

PYtest Capsules are also supplied separately in unit dose packages of 1,10 and 100.

The PYtest Capsule has a shelf life of two years. The expiration date is printed on the capsule label.

PYtest Capsules and Kit should be stored at 15°-30°C (59°-86°F) in an area designated by each individual institution's regulations.

Rx Only

Kimberly-Clark Distributed in the U.S. by Kimberly-Clark Global Sales, LLC, Roswell, GA 30076 USA In USA, please call 1-800-KCHELPS • Kimberly-Clark, Roswell, GA 30076 USA Kimberly-Clark N.V., Belgicastraat 13, 1930 Zaventem, Belgium Sponsored in Australia by Kimberly-Clark Australia Pty Limited; 52 Alfred Street, Milsons Point, NSW 2061 • 1-800-101-021©2003 KCWW. All rights reserved.

14-63-136-0-00/70080910 12/07



Contents – 1 PYtest* Capsule each containing 1 µCi C-UreaPYtest* Breath Collection Accessories C-Urea (5730 years1/2, 156 keV β-emission)For dosage information, please see package insert

This package conforms to the conditions and limitations specified in 49 CFR 173.421 for radioactive material, excepted package-limited quantity of material, UN 2910.

For In Vitro Diagnostic Use Rx Only Store at 15°–30°C (59°–86°F)

Distributed in the USA by Halyard Sales, LLC, Alpharetta, GA 30004; In USA, please call 1-844-425-9273 • halyardhealth.comHalyard Health, Inc., 5405 Windward Parkway, Alpharetta, GA 30004 USA EC|REP Haylyard Belgium BVBA, Leonardo Da Vincilaan 1, 1930 Zaventem, Belgium; Sponsored in Australia by Halyard Australia Pty Limited; 52 Alfred Street, Milsons Point, NSW 2061 *Registered Trademark or Trademark of Halyard Health, Inc., or its affiliates. © 2015 HYH. All rights reserved. 20-H1-099-0-00 / 70170138


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