Diabact UBT: Uses, Dosage & Side Effects
A non-radioactive 13C-urea breath test tablet for the in vivo diagnosis of Helicobacter pylori infection in the gastric mucosa
Diabact UBT is a prescription diagnostic product containing 50 mg of 13C-urea (carbon-13 labeled urea), used as part of the urea breath test (UBT) for the detection of active Helicobacter pylori (H. pylori) infection in the stomach. The 13C-urea breath test is considered the gold standard non-invasive test for H. pylori, with a sensitivity and specificity both exceeding 95%. The test exploits the high urease activity of H. pylori: when the labeled urea tablet is ingested, the bacterial urease enzyme breaks it down into 13CO2 and ammonia. The 13CO2 is absorbed into the bloodstream and exhaled, where it can be measured to confirm the presence of infection. Diabact UBT is used both for initial diagnosis and to confirm successful eradication following antibiotic therapy.
Quick Facts: Diabact UBT
Key Takeaways
- Diabact UBT contains 13C-urea, a non-radioactive isotope-labeled compound used in the urea breath test (UBT) to detect active Helicobacter pylori infection with over 95% accuracy for both sensitivity and specificity.
- The test is non-invasive and takes approximately 30 minutes: a baseline breath sample is collected, the tablet is swallowed with a citric acid solution, and a second breath sample is taken after 30 minutes for laboratory analysis.
- Proton pump inhibitors (PPIs) must be stopped at least 2 weeks before the test, and antibiotics or bismuth compounds must be stopped at least 4 weeks before, as these medications can cause false-negative results.
- Side effects are extremely rare and the test is considered very safe, using a naturally occurring non-radioactive carbon isotope with no radiation exposure whatsoever.
- The 13C-urea breath test is recommended by all major international gastroenterology guidelines (Maastricht VI/Florence Consensus, ACG, NICE) as a first-line non-invasive test for both initial diagnosis and confirmation of H. pylori eradication after treatment.
What Is Diabact UBT and What Is It Used For?
Diabact UBT is a diagnostic product used as part of the 13C-urea breath test (UBT), one of the most reliable and widely recommended non-invasive methods for detecting the presence of Helicobacter pylori (H. pylori) in the gastric mucosa. Each tablet contains 50 mg of 13C-urea, which is urea in which the carbon atom has been replaced with the stable, non-radioactive isotope carbon-13. Unlike carbon-14 based breath tests, the 13C-urea breath test involves no exposure to ionizing radiation, making it suitable for repeated use and for a broader range of patient populations.
Helicobacter pylori is a gram-negative, spiral-shaped bacterium that colonizes the human gastric mucosa. It was first identified in 1982 by Barry Marshall and Robin Warren, a discovery that fundamentally changed the understanding of peptic ulcer disease and earned them the Nobel Prize in Physiology or Medicine in 2005. H. pylori is one of the most common chronic bacterial infections worldwide, affecting approximately 50% of the global population, with prevalence rates ranging from 20–30% in developed countries to over 80% in some developing regions. The bacterium is a major causative factor in chronic gastritis, peptic ulcer disease (both gastric and duodenal ulcers), gastric mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric adenocarcinoma. The World Health Organization (WHO) has classified H. pylori as a Group 1 carcinogen — a definite cause of cancer in humans.
A defining characteristic of H. pylori is its exceptionally high urease activity. Urease is an enzyme that catalyzes the hydrolysis of urea into carbon dioxide (CO2) and ammonia (NH3). The ammonia produced creates a local alkaline microenvironment around the bacterium, protecting it from the highly acidic gastric juice (pH 1.5–3.5) and allowing it to survive and colonize the gastric mucosa. This urease activity is not merely a survival mechanism — it is also the biochemical basis of the urea breath test.
When a patient ingests the Diabact UBT tablet, the 13C-labeled urea reaches the stomach. If H. pylori is present in the gastric mucosa, the bacterial urease enzyme rapidly hydrolyzes the 13C-urea into 13CO2 (carbon-13 labeled carbon dioxide) and ammonia. The 13CO2 is quickly absorbed through the gastric and intestinal mucosa into the bloodstream, transported to the lungs, and exhaled in the breath. By comparing the ratio of 13CO2 to 12CO2 (the naturally abundant carbon-12 isotope) in the patient’s exhaled breath before and 30 minutes after ingestion of the tablet, the laboratory can determine whether H. pylori urease activity is present. The result is expressed as the delta over baseline (DOB) value in parts per thousand (‰). A DOB value above a defined cut-off (typically 3.5‰ to 5‰, depending on the specific protocol) indicates a positive result — i.e., the presence of active H. pylori infection.
The 13C-urea breath test has been extensively validated in clinical studies and is endorsed by all major gastroenterology guidelines as the preferred non-invasive diagnostic test for H. pylori. According to a comprehensive meta-analysis published in The Lancet Gastroenterology & Hepatology, the 13C-UBT has a pooled sensitivity of 96% (95% CI: 95–97%) and a pooled specificity of 96% (95% CI: 94–97%). These diagnostic performance characteristics make it superior to the H. pylori stool antigen test and considerably more accurate than serological (blood antibody) testing, which cannot distinguish between active and past infection.
The urea breath test with Diabact UBT is used in two main clinical scenarios: (1) Initial diagnosis — to detect active H. pylori infection in patients with dyspepsia, peptic ulcer disease, or other indications for testing as recommended by clinical guidelines (the “test-and-treat” strategy); and (2) Post-treatment eradication confirmation — to verify that H. pylori has been successfully eliminated after a course of eradication therapy. For eradication confirmation, the test should be performed at least 4 weeks after completion of antibiotic therapy and at least 2 weeks after stopping proton pump inhibitors.
What Should You Know Before Taking Diabact UBT?
Contraindications
The primary contraindication to Diabact UBT is a known hypersensitivity (allergy) to 13C-urea or any of the other ingredients in the formulation. In clinical practice, true allergic reactions to 13C-urea are exceptionally rare, as carbon-13 is a naturally occurring stable isotope found in all organic compounds in the body, typically comprising approximately 1.1% of all carbon atoms. The tablet also contains excipients such as maize starch, lactose, and magnesium stearate; patients with known allergies to any of these substances should inform their healthcare provider before taking the test.
Patients with known or suspected gastric outlet obstruction, gastroparesis (delayed gastric emptying), or conditions that significantly alter gastric physiology may obtain unreliable results, as the test depends on adequate contact between the 13C-urea substrate and the gastric mucosa. In patients who have undergone partial gastrectomy, the test may produce false-positive results due to bacterial overgrowth in the gastric remnant by urease-producing organisms other than H. pylori. In such cases, endoscopic biopsy-based testing methods may be more appropriate.
Warnings and Precautions
Several commonly used medications can suppress H. pylori urease activity or temporarily reduce bacterial load without eradicating the infection, leading to false-negative results. It is essential to observe the following washout periods before performing the test: Proton pump inhibitors (PPIs): stop at least 2 weeks before. Antibiotics: stop at least 4 weeks before. Bismuth-containing compounds: stop at least 4 weeks before. H2 receptor antagonists: stop 24–48 hours before (some guidelines recommend no washout for H2RAs).
The accuracy of the 13C-urea breath test can be significantly affected by certain medications. Proton pump inhibitors (PPIs) such as omeprazole, esomeprazole, lansoprazole, pantoprazole, and rabeprazole suppress H. pylori urease activity and can shift the bacterium into a coccoid, non-culturable form, leading to false-negative UBT results. Multiple studies have demonstrated that PPI use within 2 weeks of testing reduces the sensitivity of the UBT from approximately 96% to as low as 60–70%. Therefore, all current guidelines recommend discontinuing PPIs at least 14 days before performing the breath test.
Antibiotics (of any class) and bismuth-containing compounds (such as bismuth subsalicylate or tripotassium dicitratobismuthate) have bactericidal or bacteriostatic effects on H. pylori and must be stopped at least 4 weeks (28 days) before the test. If a patient has recently completed H. pylori eradication therapy, the Maastricht VI/Florence Consensus specifically recommends waiting at least 4 weeks after the end of antibiotic treatment and at least 2 weeks after stopping PPIs before performing a confirmation breath test.
H2 receptor antagonists (H2RAs) such as famotidine have a less pronounced effect on UBT accuracy than PPIs. While some older guidelines recommended stopping H2RAs 24–48 hours before testing, more recent evidence suggests that H2RAs do not significantly affect the sensitivity of the 13C-UBT. The most current recommendations, including the Maastricht VI Consensus (2022), state that a washout period for H2RAs is not strictly necessary, although some clinicians still prefer a 24–48 hour washout as a precaution.
Pregnancy and Breastfeeding
There are no adequate and well-controlled studies of Diabact UBT in pregnant women. Carbon-13 is a naturally occurring, non-radioactive isotope, and the 13C-urea breath test involves no ionizing radiation. The amount of 13C-urea ingested (50 mg) is extremely small and is rapidly metabolized to CO2 and ammonia, which are normal metabolic products. From a pharmacological standpoint, the risk to the fetus is considered to be negligible. However, as a general precaution with any diagnostic procedure during pregnancy, the test should only be performed if the clinical benefit clearly outweighs any potential risk. In most clinical scenarios, testing can be deferred until after delivery unless the result would significantly change the patient’s management.
It is not expected that the 13C-urea breath test would pose any risk to a breastfed infant. The labeled carbon dioxide produced by the test is exhaled in the breath and does not accumulate in breast milk in any clinically meaningful way. Breastfeeding can generally be continued normally before and after the test. However, patients should discuss any concerns with their healthcare provider.
Children and Adolescents
The 13C-urea breath test has been validated for use in children, although the minimum age and protocol may vary. The European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) and the North American Society for Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHAN) recommend the UBT as a reliable non-invasive test for H. pylori in children over 6 years of age. Some protocols have been validated in children as young as 3 years. A reduced dose of 13C-urea (25 mg instead of 50 mg) may be used in younger children to maintain test accuracy. The test procedure for children is similar to that for adults, but the child must be able to follow instructions for breath sample collection.
Driving and Operating Machinery
Diabact UBT has no known effect on the ability to drive or operate machinery. The test does not cause sedation, dizziness, or any neurological effects. Patients can drive themselves to and from the testing facility and resume all normal activities immediately after the test.
How Does Diabact UBT Interact with Other Drugs?
Unlike therapeutic medications, Diabact UBT is a diagnostic agent that is not absorbed systemically in its original form. The 13C-urea is either hydrolyzed by H. pylori urease in the stomach (producing 13CO2 and ammonia) or passes through the gastrointestinal tract intact and is eventually excreted. There are no traditional drug–drug interactions involving cytochrome P450 enzymes, drug transporters, or plasma protein binding, because 13C-urea does not undergo hepatic metabolism and does not affect the pharmacokinetics of any other medication.
However, the clinical accuracy of the urea breath test can be significantly affected by medications that alter the gastric environment or suppress H. pylori. Understanding these interactions is essential for obtaining reliable diagnostic results.
| Drug Category | Examples | Effect on Test | Required Washout |
|---|---|---|---|
| Proton Pump Inhibitors (PPIs) | Omeprazole, esomeprazole, lansoprazole, pantoprazole, rabeprazole | False-negative (suppresses urease activity and shifts bacteria to coccoid form) | At least 2 weeks |
| Antibiotics | Amoxicillin, clarithromycin, metronidazole, levofloxacin, tetracycline, rifabutin | False-negative (reduces bacterial load without complete eradication) | At least 4 weeks |
| Bismuth Compounds | Bismuth subsalicylate (Pepto-Bismol), tripotassium dicitratobismuthate | False-negative (bactericidal effect on H. pylori) | At least 4 weeks |
| H2 Receptor Antagonists | Famotidine, ranitidine, cimetidine | Minimal effect (may slightly reduce accuracy in some studies) | 24–48 hours (some guidelines: none required) |
| Antacids | Aluminum hydroxide, magnesium hydroxide, calcium carbonate | No significant effect on test accuracy | None required |
| Sucralfate | Sucralfate (Carafate) | Possible false-negative (may form a barrier over gastric mucosa) | 2 weeks recommended |
Major Interactions
The most clinically significant interaction is with proton pump inhibitors (PPIs). PPIs raise intragastric pH, which redistributes H. pylori from the antrum to the corpus and reduces bacterial urease activity. Additionally, PPIs can promote the conversion of H. pylori from its metabolically active spiral form into a dormant coccoid form that has significantly reduced urease expression. Studies have consistently shown that concurrent PPI use reduces UBT sensitivity from approximately 96% to 60–70%, meaning that up to one in three infected patients could receive a falsely negative result if PPIs are not discontinued before testing.
Antibiotics reduce the total H. pylori bacterial load in the stomach, which decreases the amount of urease available to hydrolyze the 13C-urea substrate. Even if the antibiotic does not completely eradicate the infection, the temporary suppression can be sufficient to produce a false-negative UBT result. This is why a 4-week washout period after any antibiotic use (not just anti-H. pylori regimens) is required before performing the breath test. Bismuth compounds have a direct bactericidal effect on H. pylori and similarly require a 4-week washout.
Minor Interactions
H2 receptor antagonists (H2RAs) have a much smaller effect on the UBT than PPIs. While H2RAs also reduce gastric acid secretion, they do so through a different mechanism (competitive inhibition of histamine H2 receptors on parietal cells) and do not appear to significantly affect H. pylori urease activity or bacterial morphology. The Maastricht VI/Florence Consensus (2022) states that a washout period for H2RAs is not strictly necessary before the 13C-UBT, although many clinicians still recommend a 24–48 hour washout as a conservative approach.
Simple antacids (aluminum hydroxide, magnesium hydroxide, calcium carbonate) neutralize gastric acid but do not directly affect H. pylori urease activity or bacterial load. They do not require a washout period before the breath test. However, patients should avoid taking antacids immediately before the test, as large volumes of antacid in the stomach could theoretically interfere with substrate distribution.
What Is the Correct Dosage of Diabact UBT?
Diabact UBT is not a therapeutic medication taken on a regular schedule. It is a single-dose diagnostic agent administered as part of a standardized breath test procedure under medical supervision. The entire test involves one tablet taken on one occasion, and the dosage does not change based on body weight, age, or disease severity for adult patients.
Adults
Standard Adult Dosage
Dose: One tablet containing 50 mg of 13C-urea, taken orally as a single dose.
Preparation: The patient must fast for at least 6 hours before the test (overnight fasting is preferred). No smoking or vigorous exercise on the morning of the test.
Procedure: (1) Collect baseline breath sample into the first collection container. (2) Dissolve the citric acid powder in 200 mL of water and drink the solution (this delays gastric emptying and enhances test sensitivity). (3) Immediately swallow the Diabact UBT 50 mg tablet whole with a small amount of water. Do not chew. (4) Remain seated and calm for 30 minutes. (5) Collect the post-dose breath sample into the second collection container. (6) Send both samples to the laboratory for analysis by isotope ratio mass spectrometry (IRMS) or infrared spectroscopy.
Children
Pediatric Dosage
Children aged 6–17 years: One tablet containing 50 mg of 13C-urea. The procedure is identical to the adult protocol.
Children aged 3–5 years: Some protocols recommend a reduced dose of 25 mg 13C-urea. The child must be able to cooperate with the breath collection procedure. A healthcare professional experienced in pediatric testing should supervise.
Children under 3 years: The UBT is generally not recommended in children under 3 years of age, as cooperation with the breath collection procedure may be difficult and test validation data are limited for this age group.
Elderly
Elderly Patients (65+ years)
Dose: One tablet containing 50 mg of 13C-urea. No dose adjustment is required for elderly patients. The test procedure is identical to that for younger adults.
Elderly patients may have a higher prevalence of H. pylori infection and are more likely to be taking PPIs for conditions such as gastroesophageal reflux disease. It is particularly important to ensure that PPIs have been discontinued for at least 2 weeks before performing the test in this population.
Missed Dose
The concept of a missed dose does not apply to Diabact UBT, as it is a single-dose diagnostic test administered on one occasion. If the test procedure is interrupted or a breath sample is not collected properly, the entire test should be repeated on a different day following the same preparation protocol (fasting, medication washout, etc.).
Overdose
Overdose with Diabact UBT is extremely unlikely in clinical practice, as the test is administered under medical supervision as a single 50 mg tablet. Even in the hypothetical scenario of ingesting multiple tablets, 13C-urea is a non-toxic, non-radioactive compound. The urea would be metabolized normally into carbon dioxide and ammonia through standard metabolic pathways (or by bacterial urease if H. pylori is present). The amount of ammonia generated from even several doses would be negligible compared to the body’s normal daily urea metabolism (the liver produces approximately 20–35 grams of urea per day). No cases of overdose or toxicity from 13C-urea have been reported in the medical literature.
| Patient Group | Dose | Special Considerations |
|---|---|---|
| Adults (18+ years) | 50 mg (one tablet), single dose | Standard protocol; fast 6+ hours; stop PPIs 2 weeks before |
| Children (6–17 years) | 50 mg (one tablet), single dose | Same protocol as adults; child must cooperate with breath collection |
| Children (3–5 years) | 25–50 mg, single dose (per protocol) | Reduced dose may apply; specialist supervision recommended |
| Elderly (65+ years) | 50 mg (one tablet), single dose | No dose adjustment; ensure PPI washout compliance |
| Pregnancy | 50 mg if clinically necessary | Generally deferred; no radiation risk; discuss with physician |
What Are the Side Effects of Diabact UBT?
Diabact UBT has an exceptionally favorable safety profile, which is expected given that 13C-urea is a non-pharmacologically active diagnostic substrate rather than a therapeutic agent. The 13C isotope is naturally present in the body and in all dietary carbon sources (approximately 1.1% of all carbon atoms are 13C). The 50 mg dose of 13C-urea used in the breath test is trivially small compared to the body’s daily urea turnover of 20–35 grams. Therefore, the test does not introduce any foreign or potentially harmful substance into the body.
Unlike the older 14C-urea breath test, which uses the radioactive isotope carbon-14, the 13C-urea breath test involves absolutely no ionizing radiation. This is a significant safety advantage that makes the test suitable for repeated use (for example, testing before and after eradication therapy), for use in children, and for use in pregnant women when clinically necessary.
In clinical trials and extensive post-marketing experience, adverse effects directly attributable to the 13C-urea tablet have been reported extremely rarely. The most commonly reported symptoms are mild and transient gastrointestinal complaints related to the test procedure itself rather than to the active substance:
Rare
May affect up to 1 in 1,000 people
- Mild nausea (usually related to the citric acid test meal rather than the 13C-urea tablet)
- Temporary feeling of fullness or bloating in the stomach
- Mild abdominal discomfort
Not Known
Frequency cannot be estimated from available data
- Hypersensitivity reactions to excipients (e.g., lactose intolerance in patients allergic to excipients)
- Unpleasant taste (from the citric acid test meal solution)
It is important to distinguish between symptoms caused by the diagnostic test and symptoms of the underlying condition being investigated. Patients undergoing H. pylori testing often have dyspepsia, epigastric pain, nausea, or other gastrointestinal symptoms that are manifestations of their gastric condition, not side effects of the breath test. If a patient experiences significant or persistent symptoms after the test, these are much more likely to be related to their underlying gastric condition than to the 13C-urea tablet.
While adverse effects from Diabact UBT are extremely uncommon, you should contact your healthcare provider if you experience any unexpected symptoms after the test, such as a severe allergic reaction (difficulty breathing, swelling of the face or throat, severe rash), persistent vomiting, or severe abdominal pain. These symptoms are very unlikely to be caused by the breath test and may indicate an underlying condition requiring medical attention.
The overall safety record of the 13C-urea breath test is supported by decades of clinical use worldwide. The test has been performed millions of times in clinical practice since its development in the late 1980s and early 1990s. No serious adverse events attributable to 13C-urea have been reported in the medical literature or in pharmacovigilance databases. This outstanding safety profile is one of the key reasons why the UBT remains the preferred non-invasive diagnostic test for H. pylori in international guidelines.
How Should You Store Diabact UBT?
Diabact UBT tablets should be stored at a temperature not exceeding 25°C (77°F). The tablets should be kept in their original packaging (blister pack or container) to protect them from moisture and light. Like all diagnostic products, Diabact UBT should be stored in a dry environment away from direct sunlight, heat sources, and areas with high humidity, such as bathrooms. The product should not be refrigerated or frozen unless specifically indicated on the packaging.
The expiry date is printed on the outer packaging and on the blister strip. Do not use Diabact UBT after the expiry date (marked “EXP” on the packaging). The expiry date refers to the last day of the stated month. After the expiry date, the stability and accuracy of the 13C-urea labeling cannot be guaranteed, which could lead to inaccurate breath test results.
Keep Diabact UBT out of the sight and reach of children. While 13C-urea is non-toxic, the product is a diagnostic agent that should only be used under medical supervision as part of a standardized breath test procedure. Do not dispose of unused tablets via household waste or wastewater. Ask your pharmacist about proper disposal of medicines that are no longer needed, in accordance with local regulations. These measures help protect the environment.
In clinical settings, the healthcare facility will typically store Diabact UBT according to the manufacturer’s specifications and ensure that the product is within its shelf life before administering it to patients. If you have been given a Diabact UBT kit to bring to a testing appointment, store it at room temperature and keep it in its original packaging until you arrive at the testing facility.
What Does Diabact UBT Contain?
The active substance in Diabact UBT is 13C-urea (also written as 13C-urea or carbon-13 labeled urea). Each tablet contains 50 mg of 13C-urea. Urea (chemical formula: CO(NH2)2) is a simple organic compound produced naturally by the liver as a byproduct of protein metabolism. It is the primary vehicle for nitrogen excretion in mammals. In Diabact UBT, the carbon atom in urea is replaced with carbon-13, a stable, non-radioactive isotope of carbon that comprises approximately 1.1% of all naturally occurring carbon. Carbon-13 is not artificially created; it is separated and enriched from natural carbon sources. The isotopic enrichment allows the laboratory to distinguish between 13CO2 produced by H. pylori urease hydrolysis of the test substrate and the 12CO2 that is normally present in exhaled breath from normal metabolic processes.
The excipients (inactive ingredients) in the Diabact UBT tablet typically include:
- Maize starch — a binder and disintegrant that helps the tablet maintain its structure and dissolve appropriately in the stomach
- Lactose monohydrate — a filler (diluent) used to bulk the tablet to a manageable size (patients with severe lactose intolerance should be informed, although the amount is very small)
- Magnesium stearate — a lubricant used in the tablet manufacturing process to prevent the tablet from sticking to the compression equipment
- Colloidal silicon dioxide — a glidant that improves powder flow during manufacturing
The Diabact UBT test kit typically includes, in addition to the tablet:
- Citric acid powder (or granules) — to be dissolved in water to create the test meal. The citric acid solution serves an important purpose: it delays gastric emptying, ensuring that the 13C-urea remains in contact with the gastric mucosa for an adequate time to allow urease hydrolysis if H. pylori is present. Additionally, the acidic solution promotes urease activity at the bacterial surface.
- Breath collection containers — bags, tubes, or vials for collecting the baseline and post-dose breath samples
- Instructions for use — detailed step-by-step instructions for the healthcare professional performing the test
- Sample labels and requisition forms — for proper identification and tracking of breath samples sent to the laboratory
The tablet is round, white to off-white in color, and is not coated. It should be swallowed whole with water and should not be chewed, crushed, or dissolved. The tablet is designed to dissolve in the stomach, where the 13C-urea is released and comes into contact with the gastric mucosa.
Frequently Asked Questions About Diabact UBT
The key difference is that the 13C-urea breath test (used in Diabact UBT) uses a stable, non-radioactive isotope of carbon, while the 14C-urea breath test uses a radioactive isotope. Both tests work on the same principle — detecting H. pylori urease activity — and have comparable diagnostic accuracy. However, the 13C test has significant practical advantages: it involves no radiation exposure, can be used in children and pregnant women, can be repeated without radiation concerns, and does not require special radioactive waste disposal. The 14C test uses a very small dose of radiation (approximately 1 micro-curie), which is lower than the natural background radiation received in a single day, but regulatory requirements for radioactive materials make it less convenient in many clinical settings. The 13C test is now the preferred breath test worldwide.
To confirm eradication of H. pylori after treatment, you should wait at least 4 weeks (28 days) after completing your antibiotic regimen and at least 2 weeks after stopping proton pump inhibitors (PPIs). This waiting period is critical because residual antibiotic effects can suppress H. pylori without fully eradicating it, and PPIs can suppress bacterial urease activity. Testing too soon can produce a false-negative result, falsely suggesting that the treatment was successful when the infection is still present. All major guidelines, including the Maastricht VI/Florence Consensus (2022) and the ACG Clinical Guideline (2024), recommend this waiting period for reliable eradication confirmation.
The 13C-urea breath test is considered safe from a radiation standpoint, as it uses a non-radioactive isotope with no ionizing radiation exposure. The 50 mg dose of 13C-urea is metabolically insignificant. However, as a general medical precaution, diagnostic tests during pregnancy should only be performed if the result would meaningfully change the patient’s management. In most cases, H. pylori testing can be safely deferred until after delivery. If testing during pregnancy is deemed clinically necessary by the physician (for example, in cases of active peptic ulcer disease or severe dyspepsia), the breath test is preferred over invasive endoscopic methods.
A positive result (delta over baseline value above the cut-off, typically 3.5–5‰) indicates that active H. pylori infection is present in the stomach. This means the bacterium’s urease enzyme hydrolyzed the 13C-urea, producing detectable levels of 13CO2 in the breath. A positive result typically leads to a discussion with your doctor about eradication therapy (a combination of antibiotics and a PPI for 10–14 days). A negative result (delta over baseline below the cut-off) indicates that H. pylori infection is not detected. However, false-negative results can occur if medications (PPIs, antibiotics, bismuth) have not been stopped for the required washout period. If clinical suspicion remains high despite a negative result, your doctor may recommend repeat testing or alternative diagnostic methods.
Both the 13C-urea breath test and the H. pylori stool antigen test (HpSA) are recommended by international guidelines as reliable non-invasive tests for H. pylori. In direct comparison, the UBT consistently demonstrates slightly higher sensitivity and specificity than the stool antigen test in meta-analyses (UBT: ~96% for both; HpSA: ~92–94% for both). The UBT also has some practical advantages: results are not affected by upper gastrointestinal bleeding (which can reduce stool test accuracy), and many patients find providing a breath sample more acceptable than collecting a stool sample. However, the stool antigen test is more widely available, does not require specialized equipment for sample collection, and is less expensive. The choice between the two tests often depends on local availability, patient preference, and clinical context. For eradication confirmation after treatment, the UBT is generally preferred.
No, you must fast for at least 6 hours before the Diabact UBT breath test. Overnight fasting (nothing to eat or drink after midnight, with the test performed the following morning) is the ideal preparation. Water in small amounts is usually permitted during the fasting period, but you should avoid all food, milk, juice, coffee, tea, and other beverages. Fasting ensures that the stomach is empty, which maximizes contact between the 13C-urea substrate and the gastric mucosa, and reduces the amount of background CO2 production from food digestion. You should also avoid smoking and vigorous exercise on the morning of the test, as both can affect breath CO2 levels.
References
- Malfertheiner P, Megraud F, Rokkas T, et al. Management of Helicobacter pylori infection: the Maastricht VI/Florence Consensus Report. Gut. 2022;71(9):1724–1762. doi:10.1136/gutjnl-2022-327745
- Chey WD, Howden CW, Moss SF, et al. ACG Clinical Guideline: Treatment of Helicobacter pylori Infection. American Journal of Gastroenterology. 2024;119(9):1730–1753. doi:10.14309/ajg.0000000000002968
- Best LMJ, Takwoingi Y, Siddique S, et al. Non-invasive diagnostic tests for Helicobacter pylori infection. Cochrane Database of Systematic Reviews. 2018;(3):CD012080. doi:10.1002/14651858.CD012080.pub2
- National Institute for Health and Care Excellence (NICE). Gastro-oesophageal reflux disease and dyspepsia in adults: investigation and management. NICE guideline [CG184]. Updated 2023.
- Jones NL, Koletzko S, Goodman K, et al. Joint ESPGHAN/NASPGHAN Guidelines for the Management of Helicobacter pylori in Children and Adolescents (Update 2016). Journal of Pediatric Gastroenterology and Nutrition. 2017;64(6):991–1003. doi:10.1097/MPG.0000000000001594
- Ferwana M, Abdulmajeed I, Alhajiahmed A, et al. Accuracy of urea breath test in Helicobacter pylori infection: meta-analysis. World Journal of Gastroenterology. 2015;21(4):1305–1314. doi:10.3748/wjg.v21.i4.1305
- Graham DY, Miftahussurur M. Helicobacter pylori urease for diagnosis of Helicobacter pylori infection: a mini review. Journal of Advanced Research. 2018;13:51–57. doi:10.1016/j.jare.2018.01.006
- World Health Organization (WHO). IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. Volume 61: Schistosomes, Liver Flukes and Helicobacter pylori. 1994 (reaffirmed 2023).
- Gisbert JP, Pajares JM. Review article: 13C-urea breath test in the diagnosis of Helicobacter pylori infection — a critical review. Alimentary Pharmacology & Therapeutics. 2004;20(10):1001–1017. doi:10.1111/j.1365-2036.2004.02203.x
- European Medicines Agency (EMA). Diabact UBT product information. Accessed January 2026.
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