Influence of urease activity in the intestinal tract on the results of 13C-urea breath test.

BACKGROUND AND AIM: A late rise in (13)CO2 excretion in the (13)C-urea breath test (UBT) should be found when the substrate passes rapidly through the stomach and makes contact with the colonic bacteria. The aim of this study was to evaluate the influence of intestinal urease activity on the results of the UBT. METHOD: A total of 143 subjects who were diagnosed as Helicobacter pylori negative by serology, histology and rapid urease test were recruited. At the end of endoscopy, the tip of the endoscope was placed to the second part of the duodenum and 20 mL of water containing 100 mg of (13)C-urea was sprayed into the duodenum. Breath samples were taken at baseline and at 5, 10, 20, 30 and 60 min after administration. RESULTS: Of 143 subjects, breath Delta(13)CO2 values higher than 2.5 per thousand were detected in six (4.2%), four (2.8%) and five (3.5%) subjects at 20, 30 and 60 min, respectively. There was no subject with high Delta(13)CO2 values at 5 and 10 min. Only one subject had an immediate rise at 60 min. CONCLUSION: Variability derived from urease activity in the intestinal tract appears to be minimal up to 60 min after ingestion of the test urea.

High incidence of fermentation in the digestive tract in patients with reflux oesophagitis.

OBJECTIVES: Because bacteria represent the sole source of gut hydrogen (H2) and methane (CH4), fasting breath H2 and CH4 gases have been used as markers of colonic fermentation. The presence of carbohydrates in the colonic lumen inhibits gastric and pancreatic secretions, and also influences lower oesophageal sphincter function in gastro-oesophageal reflux disease. MATERIALS AND METHODS: Studies were performed in 793 consecutive patients undergoing oesophagogastroscopy (270 men and 523 women, aged 19-85 years). A fasting breath sample (20 ml) was collected before endoscopy. At endoscopy, we intubated the stomach without inflation by air, and 20 ml of intragastric gas was collected through the biopsy channel. Next, the tip of the endoscope was inserted into the second portion of the duodenum without inflation by air, and 20 ml of intraduodenal gas was collected. H2 and CH4 concentrations of each sample were measured by gas chromatography. RESULTS: Reflux oesophagitis was found in 147 of the 793 patients. The mean values of the H2 and/or CH4 levels of samples taken from the stomach, duodenum and exhaled air were higher in patients with reflux oesophagitis than those without reflux oesophagitis. High H2 and/or CH4 levels were more frequently found in patients with reflux oesophagitis. CONCLUSIONS: We concluded that the presence of fermentation in the digestive tract was considered to be a risk factor for developing reflux oesophagitis.

Comparison of serum IgA and IgG antibodies for detecting Helicobacter pylori infection.

OBJECTIVE: Although the diagnostic utility of serum IgG antibodies to Helicobacter pylori (H. pylori) is well established, the usefulness of IgA-based tests is less well documented. The aim of this study was to evaluate two commercially available ELISAs, both for IgG and IgA. PATIENTS AND METHODS: Rapid urease test and histology analysis were performed in 183 patients. A patient was considered to be H. pylori-positive when either biopsy test was positive, and considered to be noninfected when both tests were negative. Intestinal metaplasia was determined by dye endoscopy with methylene blue. ELISA testing was performed using the EPI HM-CAP IgG and PP-CAP IgA assays and EIAgen IgG and IgA assays. RESULTS: Sensitivity was 94.7, 93.9, 94.8, and 97.0% for HM-CAP IgG, PP-CAP IgA, EIAgen IgG, and EIAgen IgA, respectively. Although sensitivity was excellent for both IgG and IgA antibodies, specificity of both IgA EIAs was low (PP-CAP 72.6%, EIAgen H. pylori IgA 59.2%). Three of 101 H. pylori-infected patients were PP-CAP positive and HM-CAP negative and four were EIAgen H. pylori IgA positive and EIAgen IgG negative. Of eight noninfected patients in whom intestinal metaplasia was found, PP-CAP IgA results were positive in three of five patients with a HM-CAP IgG negative result and EIAgen IgA was detected in one of four patients with an EIAgen IgG negative result. CONCLUSIONS: Since some patients have IgA positive but IgG negative results, great care should be taken not to underestimate the prevalence of H. pylori infection from the results of IgG serology.

Serum pepsinogens as a predicator of the topography of intestinal metaplasia in patients with atrophic gastritis.

The importance of atrophic gastritis with intestinal metaplasia is related to the fact that it increases the risk of gastric cancer development. The aim of this study is to evaluate the diagnostic potential of serum pepsinogens in predicting the topography of intestinal metaplasia. Both dye endoscopy and 13C-urea breath test were carried out in 878 subjects. Serum pepsinogen I, pepsinogen II, and IgG antibody to Helicobacter pylori were measured. The overall prevalence of intestinal metaplasia was higher in subjects with lower PG I/II ratios and lower PG I values. Based on ROC curves, a cutoff value for pepsinogen I/II ratio of less than 3.0 would have identified intestinal metaplasia with a sensitivity of 71.7% and a specificity of 66.7% in Helicobacter pylori-positive subjects. It is possible that serum pepsinogens could be used as a screening test for high-risk subjects with intestinal metaplasia.

Usefulness of gastric cancer screening using the serum pepsinogen test method.

OBJECTIVE: The measurement of serum pepsinogen has recently gained attention as a candidate for a new screening test for gastric cancer. This method is particularly attractive given its lower cost and simplicity to administer relative to photofluorography. To compare the accuracy between the two screening methods, and to elucidate the usefulness of the serum pepsinogen test method, we performed this study. METHODS: Mass screening for gastric cancer was performed using both the x-ray and pepsinogen test methods simultaneously on 286 company employees. The number of tests conducted was 5567 in total. The mean age was 48 yr in both men and women. Informed consent was taken individually. Fasting blood samples were collected, and measurement of the serum pepsinogen concentration was carried out by immunoradiometric assay. RESULTS: The percentage of those screened, who needed further examination was 11.7% for the x-ray method and 23.6% for the pepsinogen test method. The percentage of those who required further investigation, as the second step of screening, using endoscopy, was 55.4% for the x-ray method and 51.9% for the pepsinogen test method, respectively. Ten gastric cancers were detected in total. The incidence was 0.05% in the x-ray method and 0.18% in the pepsinogen test method. The rate of early gastric cancer to advanced gastric cancer was 9 to 1, that is, 90% were in the early stages. The positive predictive value was 0.8% in the x-ray method and 1.4% in the pepsinogen test method. CONCLUSIONS: The pepsinogen test method can be used as a screening test for high-risk subjects with atrophic gastritis, rather than as a tool for cancer itself. Systemic endoscopic surveillance of this group is also useful.

Hydrogen breath test as an indicator of the quality of colonic preparation for colonoscopy.

BACKGROUND: Breath hydrogen levels after ingestion of polyethylene glycol were evaluated as a method of predicting the quality of colonic preparation. METHODS: One hundred patients undergoing nonemergency colonoscopy were recruited for this study. After fasting overnight, they were instructed to ingest a polyethylene glycol solution containing 12 g lactulose at a rate of 50 mL every 5 minutes for 2 hours. During ingestion of the polyethylene glycol solution, breath samples were taken at 15-minute intervals for 240 minutes and breath hydrogen concentration was measured. RESULTS: The preparation for colonoscopy was judged to be poor in 18% and adequate in 82%. The breath hydrogen levels over 90 minutes were significantly higher in the poor group than in the adequate group. In all patients with a breath hydrogen level less than 10 parts per million at 240 minutes, the preparation was adequate. Conversely, all patients with a poor preparation had a breath hydrogen level of more than 10 ppm at 240 minutes. CONCLUSIONS: The hydrogen breath test effectively predicts adequacy of colonic preparation.

Efficacy of lactulose plus 13C-acetate breath test in the diagnosis of gastrointestinal motility disorders.

BACKGROUND: We designed a new method of measuring gastric emptying and orocecal transit time (OCTT) at the same time to assess the influence of gastric emptying upon OCTT. METHODS: Twenty-five dyspeptic patients (6 men, 19 women) with a mean age of 64.8 years (range, 25-80 years) were studied. The patients received a liquid test meal, containing 100 mg of 13C-acetate and 12g of lactulose, while they were in the sitting position after an overnight fast. Breath samples were collected at 10-min intervals of 120 min and both 13CO2 and hydrogen (H2) levels were measured. Subsequently, H2 concentrations were measured at 30-min intervals, for a total of 240 min. RESULTS: The results of gastric emptying were expressed as the time of peak 13CO2 excretion. OCTT was defined as the period between the ingestion of lactulose and a H2 peak rise of 5 ppm above the baseline value. The onset of H2 enrichment in the breath began at 90-110 min, whereas 13CO2 levels increased from the beginning, with peak enrichment values being reached after 60-80 min. OCTT was related to 13CO2 peak time. In 5 of the 25 patients, H2 breath enrichment in the 10-min sample was more than 5 ppm over the baseline value. All these 5 patients had double or triple peaks in serial breath H2 concentrations. CONCLUSIONS: The combination of the lactulose hydrogen breath test (LHBT) with the 13C-acetate breath test, which requires only breath samples, provides us with much information on the gastrointestinal tract; gastric emptying, OCTT, bacterial overgrowth in the small intestine, colonic fermentation, and oropharyngeal flora. The 13C-acetate breath test can be useful as an adjuvant test when LHBT is performed for measuring OCTT.