Urease test - what is it? Description, indication, preparation procedure, interpretation of the results

Until recently, medicine did not know the exact causes of gastritis or ulcers in the digestive tract. It was assumed that these pathologies are most often triggered by improper and irregular nutrition. And only in 2005, scientists discovered the Helicobacter pylori bacterium, which in many cases is the causative agent of gastric diseases. This microorganism can be detected using the urease test. What it is? And how is the study conducted? We will answer these questions in the article.

Description of analysis

A urease breath test can detect the presence of the Helicobacter pylori bacteria in the body. This microorganism lives in the stomach of people suffering from pathologies of the digestive system. The bacterium is contained in the saliva and plaque of the patient. Infection occurs with a kiss, violation of hygiene rules, the use of common dishes and a toothbrush with an infected person. Helicobacter pylori is the causative agent of gastritis, as well as ulcers and malignant tumors of the stomach.

The bacterium secretes a special enzyme - urease. This substance is able to react chemically with urea (urea). In this case, carbon dioxide and ammonia are formed. The urease test for Helicobacter pylori is based on this reaction. During the study, the patient orally uses urea. The doctor measures the concentration of carbon dioxide or ammonia in the exhaled air before and after taking the drug.

Method Advantages

In earlier times, the following types of studies were used to diagnose diseases caused by Helicobacter pylori:

• analysis of gastric mucus;
• blood test for antibodies to Helicobacter pylori;
• fecal examination by PCR diagnostics.

These days, a urease breath test is more commonly used. Consider the main disadvantages of the above methods:

1. Analysis of gastric mucus is an invasive variant of the urease test. What it is? The biomaterial is obtained during gastroscopy. The doctor introduces a special probe into the patient’s stomach and collects mucus for analysis. Then, the concentration of urease in the material is determined in the laboratory. This is an informative and reliable method, but the gastroscopy procedure is quite unpleasant for the patient. A urease breath test does not cause any discomfort.
2. A blood test for antibodies does not always reliably show the presence of infection. Quite often, false test results are noted.
3. The study of feces on Helicobacter pylori is an informative diagnostic method. It shows the presence of infection in 95% of cases. However, the selection of bacteria continues after recovery. In the analysis of feces, Helicobacter pylori can be determined after a pathology. According to the results of this study, it is difficult to judge the health of the patient.

We can conclude that the breath test is the most gentle and reliable way to diagnose. If the patient complies with all the necessary rules for preparing for the sample, then false results are extremely rare.

Indications

A urease breath test for Helicobacter pylori is prescribed for suspected inflammatory process in the stomach. An indication for the test is the patient's complaints about the following pathological manifestations:

1. Heartburn. With an infectious process in the digestive tract, hydrochloric acid penetrates from the stomach into the esophagus. This is accompanied by a burning sensation due to irritation of the mucosa.
2. Pain syndrome. With inflammation of the stomach, epigastric pains are pricking or pressing. Unpleasant sensations worsen after eating or during long breaks between meals.
3. Burping. The infectious process is accompanied by increased gas formation in the stomach. Excess gases, along with food particles, escape through the oral cavity. Exhaled air at the same time has a sour or unpleasant odor.
4. Plaque on the tongue. This is a characteristic sign of diseases of the digestive tract, including infectious origin. In chronic gastric pathologies, the tongue is constantly coated with a white coating. The patient feels dry and unpleasant aftertaste in his mouth. In the acute form of gastritis, a gray coating forms.
5. Dyspeptic symptoms. With an infectious inflammatory process, the digestive function of the digestive tract is disrupted. Patients are concerned about nausea, periodic vomiting, frequent diarrhea, followed by constipation, loss of appetite. Bloating of the abdominal cavity due to the accumulation of gases is often noted.

Such symptoms indicate an inflammatory process or an ulcer in the digestive tract. The test helps establish the infectious etiology of the disease.

The test is also carried out during the treatment of pathologies caused by the Helicobacter pylori bacterium. The study allows you to evaluate the effectiveness of the prescribed therapy.

How to prepare for the study

In order for these samples to be reliable, the following rules for preparing for the urease test must be observed:

1. The test is carried out on an empty stomach. The study is usually prescribed in the morning, the last meal is allowed 10-12 hours before the test. On the eve of the analysis, you can only drink pure water, but 1 hour before the test, you must stop even drinking fluid.
2. 14 days before the test, stop taking drugs that suppress the secretion of gastric juice, as well as antibiotics. 2 days before the test, it is necessary to abandon the use of antacids and analgesics.
3. Within 24 hours before the analysis, you can not eat dishes from legumes.
4. Alcohol is completely excluded 2-3 days before the test.

On the day of the study, do not smoke or chew gum. Before the test, thoroughly rinse your mouth and brush your teeth.

Study Options

How is the urease test performed? Doctors use the following test options:

• Helic-test (quick test);
• C-urease test.

Indications and rules for preparing for these types of studies are the same. Only the analysis technique differs. Next, we will consider in detail these types of studies and their decoding.

Helic Test

Helic-test is a quick test option. This is the most common method of urease test. What it is? The research methodology is as follows:

1. The sample is taken on an empty stomach. The patient is offered to exhale air into the tube. It is very important to avoid saliva entering the mouthpiece of the device. Air is collected in a special sealed bag.
2. The device records the level of carbon dioxide in the sample. The doctor determines the results of the analysis visually on a scale.
3. Then the patient is given a drink of a urea solution (0.5 g of the drug per 50 ml of water).
4. After half an hour, they take a second sample of exhaled air and again measure the concentration of carbon dioxide.

The study takes about 40 minutes. Nowadays, digital instruments are used to measure carbon dioxide levels, which instantly record sample data. Therefore, the results of the analysis are usually ready immediately after the test.

The Helik-test transcript does not indicate the quantitative concentration of CO ₂ in exhaled air. This study shows the presence or absence of Helicobacter pylori in the stomach. There are 2 options for the analysis results:

1. Positive. Indicates the presence of bacteria in the body.
2. Negative. Indicates no infection.

The reliability of the quick test is about 75%.

C-urease test

A labeled carbamide test is the most informative urease test. What it is? During the procedure, the patient is offered to drink a capsule with urea. Molecules of this substance are labeled with radioactive (C14) or non-radioactive (C13) carbon. Then, the laboratory measures the level of ammonia in the exhaled air using a gas analyzer.

It should be noted that radioactive carbon C14 does not pose a risk to the health of the patient. However, in the diagnosis of children and pregnant women use non-radioactive substance C13.

The research methodology is as follows:

1. The patient exhales air into the tube of the device, avoiding saliva entering the mouthpiece.
2. Then the patient takes a capsule with urea labeled with carbon. After this, the patient is offered to lie on his side so that the drug is distributed throughout the stomach.
3. After 10 minutes, exhaled air is again taken. When using carbon C14 it is enough to make one repeated test. If a non-radioactive substance C13 is used, then air is taken three times every 10 minutes.
4. Air samples are delivered to the laboratory for analysis.

You can get the test transcript in about 1-2 days. The concentration of ammonia and carbon dioxide is measured in ppm. The following analysis results are possible:

1. Up to 0.3 ppm. In this case, the decryption indicates a negative test result. This indicates the absence of infection.
2. More than 0.3 ppm. This is a positive analysis result. It indicates the presence of Helicobacter pylori in the body.

By the concentration of ammonia, one can also judge the degree of infection of Helicobacter pylori. Possible analysis indicators are shown in the table below:

The reliability of this test is 95 - 100%.

False results

In some cases, false urease test results are noted. What does it mean? Distorted test data indicate that the patient is not properly prepared for the study.

Most often, false-negative results of the urease test for Helicobacter pylori are noted. These samples may be affected by medications that reduce the production of gastric juice or lower acidity. These agents suppress urease secretion in Helicobacter pylori cells, and the enzyme does not react with urea. Therefore, before the breakdown, it is very important to exclude the use of such drugs.

If the doctor has doubts about the reliability of the test results, then the patient is prescribed a second study. In this case, you must carefully follow all the rules for preparing for the test.

What to do with a positive test

What to do if the test showed the presence of Helicobacter pylori? Usually in such cases, doctors additionally prescribe a gastroscopy. This examination helps to determine the prevalence and localization of the inflammatory process, as well as the presence of ulcers on the wall of the stomach.

With helicobacteriosis, patients need a course of antibiotic therapy. The reception of "Omeprazole" is also shown, this drug reduces the acidity of gastric juice. If necessary, bismuth-based anti-inflammatory drugs are included in the treatment regimen.

The prognosis of helicobacteriosis is usually favorable. This disease is successfully cured with timely therapy.