Evaluation of the rice breath hydrogen test for small intestinal bacterial overgrowth

OBJECTIVES: The aims of this study were 1) to document the sensitivity, specificity, and predictive values of the rice breath hydrogen test for small intestinal bacterial overgrowth; 2) to determine the possible influence of concurrent gastric bacterial overgrowth and gastroduodenal pH on the efficacy of this test; and 3) to investigate whether reliability is limited by an inability of small intestinal luminal flora to ferment rice or its product of hydrolysis, maltose. METHODS: Twenty adult subjects were investigated with microbiological culture of proximal small intestinal aspirate and a 3-g/kg rice breath hydrogen test. Gastroduodenal pH, the presence or absence of gastric bacterial overgrowth, and the in vitro capability of small intestinal luminal flora to ferment rice and maltose, its product of hydrolysis, were determined. RESULTS: Sensitivity of the rice breath hydrogen test for small intestinal bacterial overgrowth was 33% and remained low even when subjects with small intestinal overgrowth with oropharyngeal-type (38%) and colonic-type flora (20%) and those with concurrent small intestinal and gastric bacterial overgrowth (40%) were considered separately. Sensitivity remained suboptimal despite favorable gastroduodenal luminal pH and documented ability of bacterial isolates to ferment rice and maltose in vitro. Specificity of the rice breath hydrogen test for small intestinal bacterial overgrowth was 91%. Positive predictive value, negative predictive value, and predictive accuracy were 75%, 63%, and 65%, respectively. CONCLUSIONS: Clinical value of the rice breath hydrogen test for detecting small intestinal bacterial overgrowth is limited. The rice breath hydrogen test is not a suitable alternative to small intestinal intubation and culture of secretions for the detection of small intestinal bacterial overgrowth.     

Application of the breath hydrogen test in gastroenterology]

The diagnostic capacities of the breath hydrogen test in gastroenterology are discussed in the article. The authors describe the results of their own research--determination of the intestinal bacterial contamination in patients with chronic biliary pancreatitis with the help of the Micro H2 breath hydrogen analyzer.     

Lactulose hydrogen breath test in orocecal transit assessment

Orocecal transit time can be studied easily using the hydrogen breath test with lactulose, but the method has some important limitations. The orocecal transit time of 10 patients suffering from irritable bowel syndrome was measured twice, at a one-week interval, by breath test and scintigraphy simultaneously using an aqueous solution of 20 g lactulose containing 74 MBq of [^99mTc]DTPA. Abdominal radioactivity and alveolar hydrogen values obtained every 5 min were noted and used to obtain the following: orocecal transit time by the two methods; ileocecal lactulose flow; total and per gram of lactulose hydrogen production; mean hydrogen concentration during the right colon filling; and measurement error of the breath test with respect to the scintigraphy. In the case of the breath test, the orocecal transit time intrapatient reproducibility was better (coefficient of variation =13.5%) when a hydrogen threshold increment of 5 ppm was used; the best correlation with the scintigraphic measurement was observed at this threshold (r=0.90,P<0.001). The breath test overestimated orocecal transit time with the error correlating negatively and significantly with the total hydrogen production and, particularly, the mean hydrogen concentration (r=0.79,P<0.01): for a mean hydrogen concentration of more than 15 ppm, the error was negligible, while within this value there was a noticeable overestimation. To conclude, the lactulose hydrogen breath test is capable of giving an accurate measurement of orocecal transit time if a hydrogen threshold increment of 5 ppm is chosen and if the mean hydrogen concentration in the first 30 min of the right colon filling is taken into account.     

Evaluation of a new DNA test compared with the lactose hydrogen breath test for the diagnosis of lactase non-persistence

BACKGROUND AND AIMS: Recent publications have found that the CC genotype of the DNA variant -13910 T/C upstream of the LCT gene is associated with lactase non-persistence. We therefore compared the value of DNA testing for this variant (DNA test) with the lactose hydrogen breath test (H2 test), which is the clinical standard for the diagnosis of lactase non-persistence. PATIENTS AND METHODS: One hundred and twenty-three consecutive patients with suspected lactose malabsorption were tested for the presence of the -13910 T/C variant by polymerase chain reaction-restriction fragment length polymorphism analysis. These patients also underwent the H2 test after ingestion of 50 g lactose. RESULTS: Thirty-seven subjects had a CC genotype of the -13910 T>C polymorphism suggesting lactase non-persistence; 36 (97%) had also a positive H2 test. Eighty-six subjects had either a TC or a TT genotype suggestive of lactase persistence. Seventy-four (86%) of these tested negative on the H2 test, while 12 patients had a positive H2 test. In eight of these 12 patients duodenal biopsies showed no evidence of small bowel disease. One patient carrying a CC genotype had a negative H2 test. In this patient the rise in serum glucose after oral lactose was normal, furthermore H2 non-excretion was also excluded. CONCLUSIONS: An excellent correlation is observed between a CC genotype and a positive H2 test, whereas the correlation between a TC or TT genotype and a negative H2 test result is less strong. Analysis of the -13910 T/C variant can be considered a good test for predicting the presence of lactase non-persistence in a patient population with suspected lactose malabsorption.     

The lactulose hydrogen breath test as a diagnostic test for small-bowel bacterial overgrowth.

The lactulose hydrogen breath test has been evaluated as a diagnostic test for small-bowel bacterial overgrowth using the 14C-glycocholate breath test for comparison. Twenty-seven patients with suspected bacterial overgrowth and 37 control patients were studied. The lactulose test was positive in 8 out of 9 patients with Subsequently proven bacterial overgrowth, all of whom had positive 14C-glycocholate tests. However, 6 patients with ileal disease or resection had positive 14C-glycocholate tests but negative lactulose tests. subsequent bacteriological study of duodenal juice from these patients was negative. Negative results were obtained by both tests in the remaining 12 patients, none of whom were subsequently shown to have bacterial overgrowth. All 37 control subjects had negative lactulose tests. The lactulose breath test is a simple and promising diagnostic test for the detection of small-bowel bacterial overgrowth and, unlike the 14C-glycocholate test, has the advantage of being able to distinguish bacterial overgrowth from ileal disease.     

Comparison of bentiromide test and rice flour breath hydrogen test in the detection of exocrine pancreatic insufficiency

Bentiromide test (BT) has been recently approved in the United States for screening patients with chronic pancreatitis for exocrine insufficiency. A few reports have suggested that the rice flour breath hydrogen test (RFBHT)--i.e., breath hydrogen analysis after rice flour ingestion--may also be useful in diagnosing exocrine pancreatic insufficiency. We conducted this study to compare the diagnostic value of these two tests in chronic alcoholic (n = 14) and nutritional or tropical (n = 6) pancreatitis. False-positive results were not noted with either of these two tests in 12 healthy volunteers. BT was positive in 28.6% of patients with chronic alcoholic pancreatitis and in 16.7% of patients with tropical pancreatitis. In comparison, RFBHT was almost twice as sensitive as BT in detecting insufficiency in patients with alcoholic pancreatitis (50 vs. 28.6%) and four times as sensitive in patients with tropical pancreatitis (66.7 vs. 16.7%). Only one patient in our study had a positive BT but a negative RFBHT. We recommend RFBHT as a simple, safe, and inexpensive test in screening patients for exocrine pancreatic insufficiency.     

Alterations of the colonic flora and their effect on the hydrogen breath test

The hydrogen breath test was performed by ingestion of 20 g lactulose and analysis of end-expiratory air. Eighteen patients undergoing colonoscopy, 17 receiving antibiotics, 12 prepared for colon surgery, and 15 controls were examined. The test was repeated under control conditions in the treated patients. Eleven of 55 subjects failed to produce significant amounts of hydrogen under control conditions. This 20% proportion of non-hydrogen producers is much higher than that reported by other investigators. The hydrogen production was very markedly depressed after preparation for colonscopy and antibiotic therapy. The effect of neomycin and enemata as used in preparation for colon surgery was less marked. Hydrogen production by the colonic flora is thus subject to individual variations and may be affected by various therapeutic regimens. All these may cause false negative results when using the hydrogen breath test to evaluate carbohydrate absorption. The test should therefore not be performed for a considerable time after therapeutic manipulation of the colonic flora.     

乳果糖氢呼吸试验测定口-盲肠传递时间

目的测定功能性消化不良（ＦＤ）和肠易激综合征（ＩＢＳ）患者口－盲肠传递时间（ＯＣＴＴ）．方法应用乳果糖氢呼吸试验（ＬＨＢＴ）测定了正常人１３例，ＦＤ２０例和ＩＢＳ（其中１５例主诉腹泻，１６例主诉便秘）３１例患者的ＯＣＴＴ．结果正常人ＯＣＴＴ为９５４±１９６ｍｉｎ，ＦＤ患者（９９２±２４５ｍｉｎ）与正常人比较无显著性差异（Ｐ＞００５），但其中５例动力障碍型ＦＤ的ＯＣＴＴ则显著延长（１２９０±１２０ｍｉｎ，Ｐ＜００１），以便秘为主的ＩＢＳ患者ＯＣＴＴ显著延长（１５４４±５５７ｍｉｎ，Ｐ＜００１），以腹泻为主的ＩＢＳ患者ＯＣＴＴ显著缩短（７３１±２２２ｍｉｎ，Ｐ＜００５）．结论ＦＤ和ＩＢＳ患者存在小肠动力学异常，ＬＨＢＴ可作为辅助检查小肠动力学异常的手段之一．     

呼吸气体检测在肺癌早期诊断中的应用

肺癌仍是严重威胁人们健康和生命的疾病。肺癌的早期诊断和高危人群的筛选是降低肺癌死亡率的关键。目前临床尚缺乏常规的简易的肺癌早期诊断及动态监测手段。呼吸气体诊断(breathtest)通过检测人体呼吸气体中挥发性有机化合物(volatile organic compounds,VOC)的成分变化,可发现处于早期和可治疗阶段的肿瘤,从而潜在地降低了肺癌的死亡率,有望成为一个新兴的肺癌早期诊断手段。     

Comparison of the hyperoxic test and the alternate breath test in infants.

Peripheral chemoreceptor function has been tested using either the hyperoxic test (HT), which decreases minute ventilation (V E) by causing physiologic chemodenervation, or the alternate breath test (ABT), which induces V E alternations by delivering rapid hypoxic stimuli through breath-by-breath alternations in fractional inspired O(2) between normoxia (0.21) and hypoxia (0.15). No previous studies have compared ventilatory responses to both tests in the same infants. We hypothesized that the V E decrease during HT would be significantly related to V E alternations during ABT. Eighteen infants (postnatal age 21 +/- 14 d) underwent two 30-s HTs and two ABTs (quiet sleep, face mask, and pneumotachograph; mass spectrometry measurement of inspired and expired O(2) and CO(2) fractions; and breath-by-breath analysis). The tests were done in random order. Decreases in V E and mean inspiratory flow (tidal volume over inspiratory time, VT/TI) during HTs were significantly correlated to their respective percentage coefficients of alternation during ABTs (r = 0.69 and 0.70, respectively, p < 0.01). Principal components analysis showed that the V E and VT/TI decreases during HTs were due chiefly to a fall in VT, whereas V E and VT/TI alternations were ascribable to alternations in both VT and TI. Intraindividual coefficients of variation of V E changes were significantly lower during HTs than during ABTs. We conclude that (1) ventilatory responses to HT and ABT are significantly correlated despite differences in the mechanisms of the V E changes; (2) the better reproducibility of the V E response to HT as compared with ABT may be an advantage in clinical practice.     

Applicability of short hydrogen breath test for screening of lactose malabsorption

The gold standard for diagnosing lactose malabsorption is the H₂ hydrogen breath test (HBT). Different methods of HBT have been proposed. However, in clinical practice the HBT is often shortened to 1–2 hr without proper validation. Our objective was to establish whether the usefulness of the HBT is influenced by shortening of the test and/or by substrate variations. In 62 patients with clinically suspected lactose intolerance and a positive lactose HBT we calculated the sensitivity of the HBT depending on the duration of the HBT. To determine whether substrate variations influence the sensitivity of the HBT, in another group of 32 patients with clinically suspected lactose intolerance and a positive milk HBT, the sensitivity of the HBT was also calculated depending on the duration of the test after milk ingestion. In other unselected 97 individuals, the result of the HBT with 360 ml of whole milk supplemented with lactose was compared with a symptomatic score for lactose intolerance to evaluate the specificity of the shortened milk HBT. Breath H₂ excretion was significantly higher after lactose than after milk load (P < 0.01), and the increase in H₂ appeared earlier with lactose than with milk (60 vs 90, min respectively). HBT duration influenced the sensitivity of the test that decreased from 95% for the 3-hr HBT to 37% for the 1-hr HBT with lactose and from 80% for 3-hr HBT to 21% for 1-hr HBT with milk. The specificity was similar for the 3-hr milk HBT and the 5-hr test (67 vs 62%). In conclusion, for screening of lactose malabsorption, the HBT can be shortened to 3 hr without loss of sensitivity and specificity, when a high dose of lactose load is used.     

Role of fasting gastrointestinal motility in the variability of gastrointestinal transit time assessed by hydrogen breath test.

Gastrointestinal motility and transit time, measured by the hydrogen breath test, were simultaneously assessed in six healthy volunteers. Each subject underwent six studies on separate days. On each day motility was measured in the gastric antrum, duodenum, and proximal jejunum and 15 g of lactulose was given either by mouth during gastric phases I, II, III of the motor migrating complex or infused duodenally during duodenal phases I, II, III, one phase being studied each day in random order. Fasting activity was not interrupted by the lactulose. The lactulose transit time decreased significantly from a peak with phase I through phase II to a minimum with phase III (mean (SD) 155 (26) min v 120 (10) min v 94 (14) min, p less than 0.001). Similar results were noted when the lactulose was instilled intraduodenally (156 (23) min v 125 (19) min v 100 (17) min, p less than 0.001). No correlation was found between motility index and transit. These results suggest that different phases of fasting gastrointestinal motility are major determinants of the transit time estimated by the hydrogen breath test and explain the variability of this test in practice.     

Effect of loperamide and naloxone on mouth-to-caecum transit time evaluated by lactulose hydrogen breath test.

The effect of loperamide and naloxone on mouth-to-caecum transit time was evaluated by the lactulose hydrogen breath test in four men and four women. Each subject underwent tests during the administration of placebo, loperamide (12-16 mg po), naloxone (40 micrograms/kg/h by a three-hour intravenous infusion), and loperamide plus naloxone, carried out at intervals of one or two weeks. The transit time was significantly longer after loperamide, and this effect was antagonised by the concomitant administration of naloxone whereas naloxone administered alone had no effect on mean transit time. No clinically important side effects were reported.     

Comparison of the 1-gram (14)C-D-xylose breath test and the 50-gram hydrogen glucose breath test for diagnosis of small intestinal bacterial overgrowth

BACKGROUND/AIMS: Culture of small bowel aspirate is the most direct method and the gold standard for diagnosing small intestinal bacterial overgrowth. However, cultures are cumbersome and fluoroscopy is required for obtaining aspirate. Therefore, different breath tests such as the xylose breath test and the hydrogen breath test have been developed. There is no general agreement as to which test is to be preferred. In the only previous direct comparison between these two tests an advantage for the 1-gram-(14)C-D-xylose breath test was found. The aim of the study was to compare the 50-gram glucose hydrogen breath test and the 1-gram (14)C-D-xylose breath test in relation to results of cultures of small bowel aspirate. METHODS: Forty-six consecutive patients, mean age 57 (range 27-87) years, 12 men and 34 women, were included because of suspicion of small intestinal bacterial overgrowth. After small bowel aspiration, all patients received a solution of 1 g xylose, labelled with 50 microg (14)C-D-xylose, and 50 g glucose dissolved in 250 ml water. The concentration of breath hydrogen was analyzed every 15 min for 2 h and (14)CO(2) was analyzed every 30 min for 4 h. A positive hydrogen breath test was defined as a rise in hydrogen concentration of 15 ppm. A positive xylose test was defined as an accumulated dose 4.5% after 4 h. Two definitions for a positive culture were used, either growth of 10(5 )colonic-type bacteria/ml or growth of 10(5) bacteria/ml of any type. RESULTS: Twenty-four patients had growth of 10(5) bacteria, of whom 10 had growth of 10(5) colonic-type bacteria in small bowel aspirate. Twenty-two patients had no significant growth. The hydrogen breath test and the xylose breath test had a sensitivity for growth of 10(5) bacteria of 58 and 42%, respectively. For growth of 10(5 )colonic-type bacteria the sensitivity was 90% for the hydrogen breath test and 70% for the xylose breath test. The specificity was similar for the two tests. CONCLUSION: Although no significant difference between the two tests was found, there was a tendency in favor of the 50-gram glucose hydrogen breath test. The simplicity in combination with high sensitivity makes the hydrogen breath test suitable as a screening method to select patients for further investigation.     

Methodological aspects of the use of the hydrogen (H2) breath test

Normalization of the breath hydrogen (H2) concentration by simultaneous determination of breath carbon dioxide (CO2) and the addition of lactulose to a liquid meal have been recommended to improve the reproducibility of the hydrogen breath test. To assess the clinical relevance of these recommendations, we studied 64 children of 4 different age groups and 12 adults. Simultaneous determination of CO2 concentration and normalization of breath H2 resulted in a marked decrease of intestinal transit time and its variation in children; in adults, however, this correction was negligible. With lactulose alone, the mean coefficient of variation within individuals was only 11.7% and 13.2%, with and without H2 normalization, respectively. Therefore, the addition of a liquid meal does not seem to be necessary.     

Potential usefulness of hydrogen breath test withd-xylose in clinical management of intestinal malabsorption

Hydrogen breath tests (H₂ BT) have been used extensively to investigate intestinal dissacharidase deficiencies. A potentially useful test for assessing intestinal absorptive function, the H₂ BT withd-xylose (H₂ BT-d-xylose), has received scant attention. We report here the results of our investigation of this test in 45 patients. Fifteen patients had proved malabsorption that was due to nontropical sprue in nine, and to lymphoma, Whipple's disease, or giardiasis in the remainder. Nine patients had small-bowel bacterial overgrowth secondary to either postsurgical sequelae or intestinal dysmotility. Twenty-one patients with irritable bowel syndrome and 21 healthy individuals served as control groups. All participants ingested 25 g ofd-xylose, and alveolar breath samples were obtained thereafter at 30 min intervals for 5 hr. Breath H₂ was measured by chromatography. Basal H₂ production, peak change (Δ) and area under the curve (AUC) were calculated. Simultaneously, 5-hr urinary excretion ofd-xylose was measured by colorimetry and served as the reference test. In healthy individuals,d-xylose ingestion increased H₂ production (Δ=5.8±1.4 ppm,P<0.001). Changes were similar in patients with the irritable bowel syndrome. In contrast, the increase was of a much greater magnitude in the malabsorption group (Δ=49.9±7.2 ppm,P<0.001 vs healthy controls). AUC analysis yielded comparable results. Test performance analysis showed that, in malabsorption the H₂ BT-d-xylose had a sensitivity index of 0.86, which was identical to that of the urinaryd-xylose test. Specificity was 1 and 0.95, respectively; and predictability 1 and 0.93, respectively. All patients who responded to treatment normalized their H₂ production, whereas those who did not respond maintained their high H₂ production. In the bacterial-overgrowth group, the H₂ BT-d-xylose was only positive when the urinary excretion ofd-xylose was positive (five patients), whereas that three of the remaining four patients with normal urinary excretion ofd-xylose also had a normal breath test. We conclude that the hydrogen breath test withd-xylose is a useful, valid, and practical test for the diagnosis and follow-up of malabsorption.     

13C-galactose breath test and 13C-aminopyrine breath test for the study of liver function in chronic liver disease.

BACKGROUND AND AIMS: Liver biopsy examination is the gold standard to diagnose the presence of cirrhosis. The aim of this study was to evaluate the accuracy of both 13 C-aminopyrine breath test ( 13 C-ABT) and 13 C-galactose breath test ( 13 C-GBT) in the noninvasive assessment of the presence of cirrhosis in patients with chronic liver disease. METHODS: We evaluated 61 patients with chronic liver disease of diverse etiologies (21 compensated cirrhosis). All patients underwent 13 C-GBT and 13 C-ABT, and the results were expressed as a percentage of the administered dose of 13 C recovered per hour (%dose/h) and as the cumulative percentage of administered dose of 13 C recovered over time (%dose cumulative). Results were analyzed according to absence vs presence of cirrhosis. RESULTS: On average, 13 C-GBT %dose/h and %dose cumulative were decreased significantly in patients with compensated cirrhosis, and the same finding was observed for 13 C-ABT results from 30 to 120 minutes. 13 C-GBT %dose/h at 120 minutes had 71.4% sensitivity, 85.0% specificity, and 83.7% accuracy, whereas 13 C-ABT %dose cumulative at 30 minutes had 85.7% sensitivity, 67.5% specificity, and 77.1% accuracy for distinguishing between the 2 subgroups of patients. Combined assessment of 13 C-GBT and 13 C-ABT increased the diagnostic accuracy (80% positive predictive value) of either test alone and reached 92.5% specificity and 100% sensitivity for the diagnosis of cirrhosis. CONCLUSIONS: In patients with chronic liver disease, both 13 C-GBT and 13 C-ABT are useful for the diagnosis of cirrhosis. Combination of the tests increases the diagnostic yield of each test alone.     

Comparison of noninvasive breath hydrogen test for gastric acid secretion to standard intubation test in adults

We have developed a noninvasive test for gastric acid secretion based on the reaction of ingested magnesium metal with gastric acid to produce hydrogen gas, which is excreted in exhaled air and belches. This test was compared to the standard intubation test by performing both, on different days, in 36 adult Peruvian outpatients referred for gastric analysis; the correlation coefficient for this comparison was 0.71. The new test was repeated in nine subjects, and the resulting test-retest correlation coefficient was 0.83. The new test thus compares favorably with the standard intubation test. Because it is also noninvasive and should therefore be more acceptable to subjects, this new test may be useful for clinical evaluation and research studies on subjects in whom intubation would be difficult or unacceptable.