Source: FDA, National Drug Code (US) Revision Year: 2020
PYtest1 (14C-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 14CO2 in breath samples.
As shown in Figure 2, the PYtest1 Kit contains:
Figure 2. PYtest1 Kit:
2 The kit includes analysis by Kimberly-Clark of one balloon from one patient at one time point.
One PYtest1 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 CO2 is required to perform analysis of a breath sample. The amount of breath required to provide 1 mM of CO2varies depending on the amount of CO2 the patient is producing. Since a full balloon typically contains at least 1 mM of CO2, the balloon should be completely filled.
| 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 |
The indeterminate result should be evaluated by repeating the PYtest1or 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 PYtest1.
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
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 PYtest1. |
| Resective gastric surgery | false neg. | Isotope may empty rapidly from the stomach. |
| Resective gastric surgery | false pos. | Patient may be achlorhydric and havebacterial 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 PYtest1:
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 CLOtest1
If the capsule is damaged or appears abnormal in any way, it may give inaccurate results.
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.
PYtest1 Capsules and Kit should be stored at 15°-30°C (59°-86°F) in an area designated by each individual institution’s regulations.
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