How to Read Hydrogen Breath Test Results
J Neurogastroenterol Motil. 2011 Jul; 17(3): 312–317.
How to Translate Hydrogen Breath Tests
Uday C Ghoshal
Section of Gastroenterology, Sanjay Gandhi Postgraduate Constitute of Medical Sciences, Lucknow, India.
Received 2011 Jun 7; Revised 2011 Jun 19; Accepted 2011 Jun xx.
Abstract
Hydrogen breath tests using diverse substrates similar glucose, lactulose, lactose and fructose are being used more than and more than to diagnose small intestinal bacterial overgrowth (SIBO) and lactose or fructose malabsorption. Though quantitative culture of jejunal aspirate is considered equally golden standard for the diagnosis of SIBO, hydrogen jiff tests, in spite of their low sensitivity, are popular for their non-invasiveness. Glucose hydrogen breath test is more adequate for the diagnosis of SIBO equally conventionally accepted double-pinnacle criterion on lactulose hydrogen breath exam is very insensitive and recently described early-peak criterion is oft imitation positive. Hydrogen jiff exam is useful to diagnose various types of sugar malabsorption. Technique and estimation of dissimilar hydrogen jiff tests are outlined in this review.
Keywords: Jiff tests, Hydrogen, Intestine, small-scale, Irritable bowel syndrome
Introduction
Recently, hydrogen breath examination (HBT) has get pop in clinical practise as information technology is useful for diagnosing small intestinal bacterial overgrowth (SIBO) and saccharide intolerance such as lactose and fructose malabsorption (Table).ane Though quantitative civilisation of jejunal aspirate is considered equally golden standard for the diagnosis of SIBO, HBT is popular as it is non-invasive.1 , 2 In spite of the simplicity of performance, there is lack of uniformity regarding the interpretation of various HBTs. Therefore, technique and interpretation of ordinarily used HBTs are reviewed hither.
Tabular array
Various Hydrogen Breath Tests Used in Clinical Practice and Their Clinical Utility
Principle of Hydrogen Breath Tests
In these tests, hydrogen exhaled in the breath is estimated using a gas chromatograph. Bacteria, especially anaerobic, colonizing the large bowel in health and small-scale bowel in diseased conditions produce hydrogen past fermentation of unabsorbed carbohydrates. Though modest amount of hydrogen is produced from limited amounts of unabsorbed sugar reaching the colon, large amounts of hydrogen may exist produced if there is malaborption of carbohydrate in the small intestine allowing larger amount to reach the colon or if there is excess of bacteria in the pocket-size bowel. The hydrogen produced past the bacteria is absorbed through the wall of the small or large intestine or both. The hydrogen-containing blood travels to the lungs where the hydrogen is released and exhaled in the breath where it tin be measured. Nigh 15%-30% people have gut flora that incorporate Methanobrevibacter smithii, which converts 4 atoms of hydrogen into 1 molecule of methane.3 These subjects may not exhale much hydrogen in the breath in spite of having SIBO or carbohydrate malabsorption as excess hydrogen produced in them is converted into marsh gas. Figure 1 summarizes the principle of HBTs.
A schematic diagram that shows principle of hydrogen breath test. SIBO, modest abdominal bacterial overgrowth; ppm, parts per million.
Patient Preparation
The subjects are asked to avoid slowly absorbed carbohydrates (like breadstuff and spud) and fiber the previous nighttime as these would cause delayed excretion of hydrogen in breath.2 Cigarette smoking and exercise are avoided ii hours earlier and during the test, as hyperventilation can cause changes in breath hydrogen content.ii Pro-motility, anti-move drugs, antibiotics and other drugs that can cause SIBO including proton pump inhibitors should exist discontinued before performing breath tests.
Process of the Jiff Exam
Jiff test is performed after overnight fast. Before the test, subjects are asked to brush their teeth and rinse rima oris with antiseptic mouth wash and tap water, to eliminate an early on hydrogen peak due to activity of oral bacteria on exam sugars.two End-expiratory breath samples are collected either in bag or syringes. At the first of the test, fasting breath hydrogen is estimated 3 to 4 times and the average of these values is taken equally the basal jiff hydrogen. Subsequently, the bailiwick ingests a fixed amount of the test sugar (10 g lactulose, 100 g glucose, l g lactose or 25 g fructose). All samples of breath are analyzed for hydrogen and marsh gas every 15 minutes for ii to 4 hours. These values are written on a diary. Special computer softwares are also available to record values of the breath tests. Development of symptoms post-obit ingestion of the substrate is too noted.iv Lactose tolerance test, which involves estimation of blood saccharide in fasting state and 30-minutes after ingestion of lactose, is usually combined with lactose HBT.five
Interpretation of Breath Tests
Figure ii shows some typical HBT graphs. HBTs are interpreted as follows.
Some typical hydrogen breath examination graphs are shown. It shows glucose hydrogen breath examination negative for small intestinal bacterial overgrowth (SIBO) (A), glucose hydrogen jiff test positive for SIBO (B), lactose hydrogen breath and tolerance test negative for lactose malabsorption (C) and lactose hydrogen breath and tolerance test positive for lactose malabsorption (D). It shows a graph negative for fructose malabsorption (E) and a graph positive for fructose malabsorption (F). ppm, parts per meg; FBS, fasting blood sugar; PPBS, post-prandial blood sugar.
High Basal Jiff Hydrogen
If average basal values of breath hydrogen is more than 16 parts per million (ppm), information technology is more often than not considered as a loftier value.six The substrate may non exist administered if basal breath hydrogen is high and the test would exist abandoned. In such situation, the test is repeated with proper training again. Some investigators considered high basal breath hydrogen to be suggestive of SIBO7 though evidences available are contradictory.half dozen
Diagnosis of Small-scale Intestinal Bacterial Overgrowth on Glucose and Lactulose Hydrogen Breath Test
SIBO is diagnosed on glucose HBT if there is a rising in breath hydrogen by 12 ppm higher up the basal. The sensitivity and specificity of this criterion to diagnose SIBO are xl% and fourscore%, respectively.2 Conventionally, double peak in lactulose HBT (1 due to SIBO and the other from colon) is considered equally diagnostic of SIBO. Sensitivity and specificity of lactulose HBT to diagnose SIBO using this conventional criterion are 31% and 86%, respectively when considering the quantitative culture of jejunal aspirate (bacterial colony count ≥ 105 CFU/mL) every bit gold standard.2
Glucose or Lactulose Hydrogen Breath Test to Diagnose Small Intestinal Bacterial Overgrowth?
A double-peak criteria on lactulose HBT as mentioned above is only 31% sensitive to diagnose SIBO.two Pimentel et alviii suggested that a rise in breath hydrogen twenty ppm in a higher place basal levels within 90 minutes subsequently ingestion of lactulose should be considered as diagnostic of SIBO. This benchmark has not been validated. Moreover, it presumes that mouth-to-cecum transit time is always greater than 90 minutes, so that a peak in jiff hydrogen within 90 minutes subsequently lactulose ingestion must be due to bacterial fermentation in the small bowel. Notwithstanding, this assumption is not correct. Oral cavity-to-cecum transit time in Asian populations is oft shorter than 90 minutes. For example, in our written report, median oral cavity-to-cecum transit time in 12 healthy Indian subjects was 65 minutes (range 40 to 110 minutes).9 In a study of 45 healthy Taiwanese, mean mouth-to-cecum transit time was 85 minutes (standard deviation 37).10 Therefore, a large proportion of these healthy subjects would have been diagnosed as having SIBO if Pimentel'southward criterion had been employed. Hence, lactulose HBT should non be used to diagnose SIBO. Fifty-fifty the double-peak benchmark to diagnose SIBO on lactulose HBT has lower sensitivity than glucose HBT (31% vs forty%).2 Therefore, glucose HBT should be used for diagnosing SIBO.
Limitations of Hydrogen Breath Test to Diagnose Small Intestinal Bacterial Overgrowth
There are several limitations of HBT for the diagnosis of SIBO.
(1) HBT with lactulose may be able to diagnose only one-third of patients with SIBO.2 Since glucose is captivated completely in the upper pocket-size intestine, it may not be able to diagnose SIBO of the distal minor intestine (ileum).xi A major problem is that at that place is no "gold standard" for the diagnosis of SIBO since culture of the bacteria has its ain limitations, equally only thirty% of gut leaner are culturable.11 However, in our study we have plant GHBT to be highly specific for diagnosis of SIBO.2 Hence, information technology is important to realize that GHBT can underestimate but is unlikely to overestimate SIBO.
(ii) There may be similarities in the pattern of gas product with SIBO and rapid intestinal transit, thus making distinctions difficult.
(3) Some normal individuals may have slow transit through the pocket-size intestine leading to prolonged testing, up to five hours and many individuals may not like to undergo such a time consuming procedure.
(4) A proportion of individuals have bacteria that do non produce hydrogen just produce other gases such as methyl hydride and hydrogen sulphide; therefore, their SIBO, if present, may not be detected with the HBT.three Estimation of methane may be useful in such situation. At that place is no commercially available car currently that measures hydrogen sulphide.
(v) Some individuals may produce a combination of hydrogen and methyl hydride. At that place is much less experience with methane as compared with hydrogen for the diagnosis of SIBO. Still, the production of methyl hydride is more than circuitous than the production of hydrogen. Therefore, it is not clear if the pattern of methane production later on ingestion of sugars tin exist interpreted in the same way as hydrogen production. Furthermore, all the equipments available in the market for HBTs do not accept facilities for estimation of methane. As mentioned to a higher place, the equipments that have facilities for estimation of methane equally well as hydrogen are superior for HBT. Methyl hydride is a mark of constipation.12
(half dozen) A positive HBT may non always hateful that a patient's symptoms are caused past SIBO. The only fashion to establish whether the symptoms are acquired by SIBO is to treat and eradicate the bacteria. If the symptoms disappear, information technology is likely that SIBO rather than the underlying disease is responsible for the symptoms.
Lactulose Hydrogen Breath Exam to Approximate Oro-Cecal Transit Time
The fourth dimension interval between ingestion of lactulose and rise in jiff hydrogen 20 ppm above basal is a measure of oro-cecal transit time. It is of import to note that value of breath hydrogen to diagnose an aberration is generally higher if fermentation of the substrate occurs in the colon rather than small intestine. For this reason, the cut-off value of hydrogen to gauge oro-cecal transit fourth dimension, lactose and fructose malabsorption is 20 ppm above basal; in contrast, the cut-off value of hydrogen to diagnose bacterial overgrowth in the small intestine is 12 ppm above basal. Recently, in a report in which lactulose HBT was compared with radio-nuclide scintigraphic method for estimation of oro-cecal transit time, the sometime was shown to accept reasonable accuracy for this purpose.13
Lactose Hydrogen Jiff test for Diagnosis of Lactose Malabsorption
Rising in hydrogen by 20 ppm higher up basal afterward lactose ingestion is considered every bit positive lactose HBT. Failure of blood carbohydrate to rise past 20 mg/dL at thirty minutes afterward ingestion of lactose is considered as positive lactose tolerance test, which is indicative of lactose malabsorption.iv , 5
There are some bug in the current protocol for lactose HBT. Some data suggest that lactose tolerance test may be as proficient as or more sensitive than lactose HBT. Lactose dose of 50 g, as suggested in the current protocol, may be too high and non-physiological. This may lead to overestimation of frequency of lactose malabsorption which may non always exist clinically important in areas of the world where frequency of the condition is likewise loftier.4
Interpretation of Fructose Hydrogen Breath Test
Ascent in hydrogen by 20 ppm above basal after fructose ingestion is considered every bit positive fructose HBT.xiv
Clinical Importance of Breath Gas Profile
Some data advise that basal breath hydrogen both in fasting land and post-obit ingestion of a substrate is higher among patients with irritable bowel syndrome, specially in those with diarrhea-predominant disease than controls.xv In contrast, people with constipation may have loftier methyl hydride.3 Therefore, hydrogen may exist a biomarker for diarrhea and methane of constipation.6 , 12 , xv Reduction of methane by rifaximin may improve constipation.12 Hydrogen may as well contribute to development of intestinal bloating.
Conclusion
HBTs are easy to perform and are non-invasive. These may be useful to understand aberrant pathophysiology such every bit SIBO and carbohydrate malabsorption contributing to symptoms in patients presenting with irritable bowel syndrome. It is suggested that uniform criteria should be adult and used for diagnosis of various disorders by HBTs.
Footnotes
Fiscal back up: None.
Conflicts of interest: None.
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Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3155069/
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