Measurement of hepatic functional mass by means of ^(13)C-methacetin and ^(13)C-phenylalanine breath tests in chronic liver disease: Comparison with Child-Pugh score and serum bile acid levels

AIM: To evaluate and compare the clinical usefulness of 13C-phenylalanine and 13C-methacetin breath tests in quantitating functional hepatic mass in patients with chronic liver disease and to further compare these results with those of conventional tests, Child-Pugh score and serum bile acid levels.METHODS: One hundred and forty patients (50 HCV-related chronic hepatitis, 90 liver cirrhosis patients) and 40 matched healthy controls were studied. Both breath test and routine liver test, serum levels of cholic and chenodeoxycholic acid conjugates were evaluated.RESULTS: Methacetin breath test, expressed as 60 min cumulative percent of oxidation, discriminated the hepatic functional capacity not only between controls and liver disease patients, but also between different categories of chronic liver disease patients. Methacetin breath test was correlated with liver function tests and serum bile acids.Furthermore, methacetin breath test, as well as serum bile acids, were highly predictive of Child-Pugh scores. The diagnostic power of phenylalanine breath test was always less than that of methacetin breath test.CONCLUSION: Methacetin breath test represents a safe and accurate diagnostic tool in the evaluation of hepatic functional mass in chronic liver disease patients.

Breath tests and irritable bowel syndrome

Breath tests are non-invasive tests and can detect H2 and CH4 gases which are produced by bacterial fermentation of unabsorbed intestinal carbohydrate and are excreted in the breath. These tests are used in the diagnosis of carbohydrate malabsorption, small intestinal bacterial overgrowth, and for measuring the orocecal transit time. Malabsorption of carbohydrates is a key trigger of irritable bowel syndrome (IBS)-type symptoms such as diarrhea and/or constipation, bloating, excess flatulence, headaches and lack of energy. Abdominal bloating is a common nonspecific symptom which can negatively impact quality of life. It may reflect dietary imbalance, such as excess fiber intake, or may be a manifestation of IBS. However, bloating may also represent small intestinal bacterial overgrowth. Patients with persistent symptoms of abdominal bloating and distension despite dietary interventions should be referred for H2 breath testing to determine the presence or absence of bacterial overgrowth. If bacterial overgrowth is identified, patients are typically treated with antibiotics. Evaluation of IBS generally includes testing of other disorders that cause similar symptoms. Carbohydrate malabsorption (lactose, fructose, sorbitol) can cause abdominal fullness, bloating, nausea, abdominal pain, flatulence, and diarrhea, which are similar to the symptoms of IBS. However, it is unclear if these digestive disorders contribute to or cause the symptoms of IBS. Research studies show that a proper diagnosis and effective dietary intervention significantly reduces the severity and frequency of gastrointestinal symptoms in IBS. Thus, diagnosis of malabsorption of these carbohydrates in IBS using a breath test is very important to guide the clinician in the proper treatment of IBS patients.

Evaluation of urea breath test as a diagnostic tool for Helicobacter pylori infection in adult dyspeptic patients

In this editorial,we discuss the article in the World Journal of Gastroenterology.The article conducts a meta-analysis of the diagnostic accuracy of the urea breath test(UBT),a non-invasive method for detecting Helicobacter pylori(H.pylori)infection in humans.It is based on radionuclide-labeled urea.Various methods,both invasive and non-invasive,are available for diagnosing H.pylori infection,inclu-ding endoscopy with biopsy,serology for immunoglobulin titers,stool antigen analysis,and UBT.Several guidelines recommend UBTs as the primary choice for diagnosing H.pylori infection and for reexamining after eradication therapy.It is used to be the first choice non-invasive test due to their high accuracy,specificity,rapid results,and simplicity.Moreover,its performance remains unaffected by the distribution of H.pylori in the stomach,allowing a high flow of patients to be tested.Despite its widespread use,the performance characteristics of UBT have been inconsistently described and remain incompletely defined.There are two UBTs available with Food and Drug Administration approval:The 13C and 14C tests.Both tests are affordable and can provide real-time results.Physicians may prefer the 13C test because it is non-radioactive,compared to 14C which uses a radioactive isotope,especially in young children and pregnant women.Although there was heterogeneity among the studies regarding the diagnostic accuracy of both UBTs,13C-UBT consistently outperforms the 14C-UBT.This makes the 13C-UBT the preferred diagnostic approach.Furthermore,the provided findings of the meta-analysis emphasize the significance of precise considerations when choosing urea dosage,assessment timing,and measurement techniques for both the 13C-UBT and 14C-UBT,to enhance diagnostic precision.

Urea breath test for Helicobacter pylori infection in adult dyspeptic patients: A meta-analysis of diagnostic test accuracy

BACKGROUND Helicobacter pylori(H.pylori)infection has been well-established as a significant risk factor for several gastrointestinal disorders.The urea breath test(UBT)has emerged as a leading non-invasive method for detecting H.pylori.Despite numerous studies confirming its substantial accuracy,the reliability of UBT results is often compromised by inherent limitations.These findings underscore the need for a rigorous statistical synthesis to clarify and reconcile the diagnostic accuracy of the UBT for the diagnosis of H.pylori infection.AIM To determine and compare the diagnostic accuracy of 13C-UBT and 14C-UBT for H.pylori infection in adult patients with dyspepsia.METHODS We conducted an independent search of the PubMed/MEDLINE,EMBASE,and Cochrane Central databases until April 2022.Our search included diagnostic accuracy studies that evaluated at least one of the index tests(^(13)C-UBT or ^(14)C-UBT)against a reference standard.We used the QUADAS-2 tool to assess the methodo-logical quality of the studies.We utilized the bivariate random-effects model to calculate sensitivity,specificity,positive and negative test likelihood ratios(LR+and LR-),as well as the diagnostic odds ratio(DOR),and their 95%confidence intervals.We conducted subgroup analyses based on urea dosing,time after urea administration,and assessment technique.To investigate a possible threshold effect,we conducted Spearman correlation analysis,and we generated summary receiver operating characteristic(SROC)curves to assess heterogeneity.Finally,we visually inspected a funnel plot and used Egger’s test to evaluate publication bias.endorsing both as reliable diagnostic tools in clinical practice.CONCLUSION In summary,our study has demonstrated that ^(13)C-UBT has been found to outperform the ^(14)C-UBT,making it the preferred diagnostic approach.Additionally,our results emphasize the significance of carefully considering urea dosage,assessment timing,and measurement techniques for both tests to enhance diagnostic precision.Nevertheless,it is crucial for researchers and clinicians to evaluate the strengths and limitations of our findings before implementing them in practice.

Dynamic carbon 13 breath tests for the study of liver function and gastric emptying

In gastroenterological practice,breath tests(BTs)are diagnostic tools used for indirect,non-invasive assessment of several pathophysiological metabolic processes,by monitoring the appearance in breath of a metabolite of a specific substrate.Labelled substrates originally employed radioactive carbon 14(^(14)C)and,more recently,the stable carbon 13 isotope(^(13)C)has been introduced to label specific substrates.The ingested^(13)C-substrate is metabolized,and exhaled^(13)CO_(2)is measured by mass spectrometry or infrared spectroscopy.Some^(13)C-BTs evaluate specific(microsomal,cytosolic,and mitochondrial)hepatic metabolic pathways and can be employed in liver diseases(i.e.simple liver steatosis,non-alcoholic steato-hepatitis,liver fibrosis,cirrhosis,hepatocellular carcinoma,drug and alcohol effects).Another field of clinical application for^(13)C-BTs is the assessment of gastric emptying kinetics in response to liquids(^(13)C-acetate)or solids(^(13)C-octanoic acid in egg yolk or in a pre-packed muffin or the^(13)C-Spirulina platensis given with a meal or a biscuit).Studies have shown that^(13)C-BTs,used for gastric emptying studies,yield results that are comparable to scintigraphy and can be useful in detecting either delayed-(gastroparesis)or accelerated gastric emptying or changes of gastric kinetics due to pharmacological effects.Thus,^(13)C-BTs represent an indirect,cost-effective and easy method of evaluating dynamic liver function and gastric kinetics in health and disease,and several other potential applications are being studied.

Ability of lactulose breath test results to accurately identify colorectal polyps through the measurement of small intestine bacterial overgrowth

BACKGROUND While colorectal polyps are not cancerous,some types of polyps,known as adenomas,can develop into colorectal cancer over time.Polyps can often be found and removed by colonoscopy;however,this is an invasive and expensive test.Thus,there is a need for new methods of screening patients at high risk of developing polyps.AIM To identify a potential association between colorectal polyps and small intestine bacteria overgrowth(SIBO)or other relevant factors in a patient cohort with lactulose breath test(LBT)results.METHODS A total of 382 patients who had received an LBT were classified into polyp and non-polyp groups that were confirmed by colonoscopy and pathology.SIBO was diagnosed by measuring LBTderived hydrogen(H)and methane(M)levels according to 2017 North American Consensus recommendations.Logistic regression was used to assess the ability of LBT to predict colorectal polyps.Intestinal barrier function damage(IBFD)was determined by blood assays.RESULTS H and M levels revealed that the prevalence of SIBO was significantly higher in the polyp group than in the non-polyp group(41%vs 23%,P<0.01;71%vs 59%,P<0.05,respectively).Within 90 min of lactulose ingestion,the peak H values in the adenomatous and inflammatory/hyperplastic polyp patients were significantly higher than those in the non-polyp group(P<0.01,and P=0.03,respectively).In 227 patients with SIBO defined by combining H and M values,the rate of IBFD determined by blood lipopolysaccharide levels was significantly higher among patients with polyps than those without(15%vs 5%,P<0.05).In regression analysis with age and gender adjustment,colorectal polyps were most accurately predicted with models using M peak values or combined H and M values limited by North American Consensus recommendations for SIBO.These models had a sensitivity of≥0.67,a specificity of≥0.64,and an accuracy of≥0.66.CONCLUSION The current study made key associations among colorectal polyps,SIBO,and IBFD and demonstrated that LBT has moderate potential as an alternative noninvasive screening tool for colorectal polyps.

Effects of ethanol and sex on propionate metabolism evaluated via a faster ^(13)C-propionate breath test in rats

BACKGROUND Alcoholism is regarded as a risk factor for vitamin B_(12)(VB_(12))deficiency.Because V B_(12) serves as a coenzyme of methylmalonyl-CoA mutase,a key enzyme in propionate metabolism,the ^(13)C-propionate breath test(PBT)has been studied as a non-invasive diagnostic modality for VB_(12) deficiency.However,the conventional PBT requires 2 h,which is inconvenient in clinical practice.We hypothesized that a faster PBT can be used to evaluate propionate metabolism and is more easily adaptable for clinical practice.AIM To evaluate a faster PBT for assessing the effects of long-term ethanol consumption on propionate metabolism in ethanol-fed rats(ERs).METHODS ERs were obtained by replacing standard drinking water(for control rats,CRs)with 16%ethanol solution in descendants of F344/DuCrj rats.Faster PBT was performed by administering ^(13)C-propionate aqueous solution to male and female ERs and CRs by inserting a metal tubule from the mouth to the stomach;exhaled gas was collected in a bag to measure its ^(13)CO_(2)/12CO_(2) isotope ratio via infrared isotope spectrometry.Serum VB_(12) and alanine transaminase(ALT)levels were measured via chemiluminescence immunoassay and the lactate dehydrogenaseultraviolet method,respectively.We evaluated statistical differences in mean body weight,change in ^(13)CO_(2)(Δ^(13)CO_(2)‰),peakΔ^(13)CO_(2)‰,and serum VB_(12) and ALT,between males and females and between ERs and CRs using the t-test and Mann-Whitney U test for normally and non-normally distributed variables,respectively.RESULTS Males weighed significantly more than females(P<0.001);CRs weighed significantly more than ERs(P<0.008).Δ^(13)CO_(2) reached a peak(C_(max))at 20 min and 30 min in females and males,respectively,decreasing after 20-30 min without rebound in all groups.Males had significantly higher C_(max) andΔ^(13)CO_(2) at 15-45 min than females(P<0.05;for all pairs).Propionate metabolism was enhanced in male ERs relative to male CRs,whereas metabolism did not differ markedly between ERs and CRs for females.Males had higher serum VB_(12) levels than females,without prominent differences between the ER and CR groups.Male CRs had notably higher ALT levels than male ERs.Thus,chronic ethanol consumption may trigger fatty acid production via intestinal bacteria and changes in gut microbiome composition.CONCLUSION Faster PBT shows that 16%ethanol consumption promotes propionate metabolism without inducing liver injury.This PBT may be used clinically to evaluate gut flora status.

Early detection and intervention in diabetic gastroparesis:Role of body surface gastric mapping

Diabetic gastrointestinal neuropathy is a diabetes-related complication,associated with a complex interplay of hyperglycemic damage,autoimmune responses,oxidative stress,gastrointestinal hormones,and vascular insufficiency.Patients with diabetes should be monitored and therapeutic intervention introduced to prevent neuropathy due to diabetes prior to“the point of no return”.Determining gastric bioelectrical activity by body surface gastric mapping may be a promising option to monitor diabetic gastrointestinal neuropathy.

Breath test for differential diagnosis between small intestinal bacterial overgrowth and irritable bowel disease:An observation on non-absorbable antibiotics

AIM： To estimate the prevalence of small intestine bacterial overgrowth （SIBO） among patients with an earlier diagnosis of irritable bowel disease （IBS） in our geographical area, and to collect information on the use of locally acting non-absorbable antibiotics in the management of SIBO. METHODS： A non-interventional study was conducted in 73 consecutive patients with a symptom-based diagnosis.. RESULTS： When the patients underwent a ＂breath test＂, 33 （45.2%） showed the presence of a SIBO. Arcer treatment with rifaximin 1200 mg/d for seven days in 32 patients, 19 （59.4%） showed a negative ＂breath test＂ one week later as well as a significant reduction of symptoms, thus confirming the relationship between SIBO and many of the symptoms claimed by patients. In the other 13 patients, ＂breath test＂ remained positive, and a further cycle of treatment with ciprofloxacin 500 mg/d was given for 7 additional days, resulting in a negative ＂breath test＂ in one patient only. CONCLUSION： （1） about half of the patients with a symptomatic diagnosis of IBS have actually SIBO, which is responsible for most of the symptoms attributed to IBS; （2） only a ＂breath test＂ with lactulose （or with glucose in subjects with an intolerance to lactose） can provide a differential diagnosis between IBS and SIBO, with almost identical symptoms; and （3） the use of non-absorbable antibiotics may be useful to reduce the degree of SIBO and related symptoms; it must be accompanied, however, by the correction of the wrong alimentary habits underlying SIBO.

Breath and string test: A diagnostic package for the identification of treatment failure and antibiotic resistance of Helicobacter pylori without the necessity of upper gastrointestinal endoscopy

AIM: Helicobacter pylori (H pylori) resistance after failed eradication has a major impact on the outcome of a further treatment regimen. The aim of this study was to assess the validity of a non-invasive strategy using the 13C-urea breath test (UBT) and the gastric string test in identifying post-treatment resistance of H pylori. METHODS: The UBT was routinely performed 4 to 6 wk after H pylori eradication therapy. Forty-two patients (24 females, 18 males, mean age 48 years) with a positive UBT were included in the study. A gastric string test using a capsule containing a 90 cm-long nylon fiber was performed. Before the capsule was swallowed, the free end of the string was taped to the cheek. After one hour in the stomach, the string was withdrawn. The distal 20 cm of the string was inoculated onto an agar plate and processed under micro-aerophilic conditions. Following the string test, upper gastrointestinal endoscopy was performed to obtain gastric biopsies for conventional culture. RESULTS: H pylori was successfully cultured from the gastric string in 34 patients (81%), but not in 5 patients due to contamination with oropharyngeal flora. H py/oriwas cultured from the gastric biopsies obtained at endoscopy in 39 patients (93%). CONCLUSION: The UBT followed by the gastric string test in the case of treatment failure is a valid diagnostic strategy with the aim of determining the post-therapeutic antibiotic resistance of H pylori with little inconvenience to the patient. Upper Gl-endoscopy can be avoided in several cases by applying consequently this diagnostic package.

Point-of-care continuous ^(13)C-methacetin breath test improves decision making in acute liver disease: Results of a pilot clinical trial

AIM: To assess the role of the 13C-methacetin breath test (MBT) in patients with acute liver disease. METHODS: Fifteen patients with severe acute liver disease from diverse etiologies were followed-up with 13C-MBT during the acute phase of their illnesses (range 3-116 d after treatment). Patients fasted for 8 h and ingested 75 mg of methacetin prior to the MBT. We compared results from standard clinical assessment, serum liver enzymes, synthetic function, and breath test scores. RESULTS: Thirteen patients recovered and two patients died. In patients that recovered, MBT parameters improved in parallel with improvements in lab results. Evidence of consistent improvement began on day 3 for MBT parameters and between days 7 and 9 for blood tests. Later convergence to normality occurred at an average of 9 d for MBT parameters and from 13 to 28 d for blood tests. In both patients that died, MBT parameters remained low despite fluctuating laboratory values. CONCLUSION: The 13C-MBT provides a rapid, noninvasive assessment of liver function in acute severe liver disease of diverse etiologies. The results of this pilot clinical trial suggest that the MBT may offer greater sensitivity than standard clinical tests for managing patients with severe acute liver disease.

Validity and cost comparison of ^(14)carbon urea breath test for diagnosis of H Pylori in dyspeptic patients

AIM： To validate and compare the cost of microdose ^14C urea breath test （UBT） with histology and rapid urease test for the diagnosis of H Py/ori. METHODS： Ninety-four consecutive patients with dyspeptic symptoms undergoing gastroscopy were enrolled. Gastric biopsies were taken for histology and rapid urease test. UBT was performed after gastroscopy by microdose ^14 urea capsules. Sensitivity, specificity and accuracy of UBT were calculated and compared with histology and rapid urease test. Cost comparison of these tests was also performed. RESULTS： H pylori was diagnosed by histology and rapid urease test in 66 （70%） and 61 （65%） patients, while ^14C UBT detected infection in 63 （67%）. Accuracy of UBT was 93% in comparison with histology while its positive and negative predictive values were 97% and 84%, respectively. Comparison of ^14C UBT with rapid urease test gives an accuracy of 96%, with positive and negative predictive values of 95% and 97%, respectively. These results were highly reproducible with a Kappa test （P value 〈 0.001）. Cost of histology or rapid urease test with gastroscopy was 110 USD or 95 USD respectively while the cost of UBT was 15 USD.CONCLUSION： Microdose ^14C UBT was comparable to histology and rapid urease test. ^14C UBT is an economical, self sufficient and suitable test to diagnose active Hpylori infection in less developed countries.

An optimized ^(13)C-urea breath test for the diagnosis of H pylori infection

AIM： To validate an optimized ^13C-urea breath test （^13C-UBT） protocol for the diagnosis of H pylori infection that is cost-efficient and maintains excellent diagnostic accuracy. METHODS： 70 healthy volunteers were tested with two simplified ^13C-UBT protocols, with test meal （Protocol 2） and without test meal （Protocol 1）. Breath samples were collected at 10, 20 and 30 rain after ingestion of 50 mg ^13C-urea dissolved in 10 mL of water, taken as a single swallow, followed by 200 mL of water （pH 6.0） and a circular motion around the waistline to homogenize the urea solution. Performance of both protocols was analyzed at various cut-off values. Results were validated against the European protocol. RESULTS： According to the reference protocol, 65.7% individuals were positive for H pylori infection and 34.3% were negative. There were no significant differences in the ability of both protocols to correctly identify positive and negative H pylori individuals. However, only Protocol 1 with no test meal achieved accuracy, sensitivity, specificity, positive and negative predictive values of 100%. The highest values achieved by Protocol 2 were 98.57%, 97.83%, 100%, 100% and 100%, respectively.CONCLUSION： A 10 min, 50 mg ^13C-UBT with no test meal using a cut-off value of 2-2.5 is a highly accurate test for the diagnosis of H pylori infection at a reduced cost.

Modified Helicobacter test using a new test meal and a 13C-urea breath test in Helicobacter pylori positive and negative dyspepsia patients on proton pump inhibitors

AIM To determine the sensitivity and specificity of the ^(13)C-urea breath test(UBT) in patients taking proton pump inhibitors(PPIs), using a new test meal Refex. METHODS One hundred and fourteen consecutive patients with dyspepsia, 53 Helicobacter pylori(H. pylori) positive, 49 H. pylori negative, were included in the study. The patients were then given esomeprazole 40 mg for 29 consecutive days, and the ^(13)C-UBT with the new test meal was performed the next morning. RESULTS The sensitivity of the ^(13)C-UBT with a cut off 2.5‰ was92.45%(95%CI: 81.79%-97.91%) by per-protocol(PP) analysis and 78.13 %(95%CI: 66.03%-87.49%) by intention-to-treat(ITT) analysis. The specificity of the ^(13)C-UBT test was 96.00 % in the ITT population(95%CI: 86.29%-99.51%) and 97.96% in the PP population(95%CI: 89.15%-99.95%).CONCLUSION The new test meal based ^(13)C-UBT is highly accurate in patients on PPIs and can be used in those unable to stop their PPI treatment.

Cost effectiveness analysis of population-based serology screening and ^(13)C-Urea breath test for Helicobacter pylori to prevent gastric cancer:A markov model

AIM:To compare the costs and effectiveness of no screening and no eradication therapy, the population- based Helicobacter pylori (H pylori) serology screening with eradication therapy and 13C-Urea breath test (UBT) with eradication therapy. METHODS:A Markov model simulation was carried out in all 237 900 Chinese males with age between 35 and 44 from the perspective of the public healthcare provider in Singapore. The main outcome measures were the costs, number of gastric cancer cases prevented, life years saved, and quality-adjusted life years (QALYs) gained from screening age to death. The uncertainty surrounding the cost-effectiveness ratio was addressed by one-way sensitivity analyses. RESULTS:Compared to no screening, the incremental cost-effectiveness ratio (ICER) was $16 166 per life year saved or $13 571 per QALY gained for the serology screening, and $38 792 per life year saved and $32 525 per QALY gained for the UBT. The ICER was $477 079 per life year saved or $390 337 per QALY gained for the UBT compared to the serology screening. The cost- effectiveness of serology screening over the UBT was robust to most parameters in the model. CONCLUSION:The population-based serologyscreening for H pylori was more cost-effective than the UBT in prevention of gastric cancer in Singapore Chinese males.

Capsule ^(13)C-urea breath test for the diagnosis of Helicobacter pylori infection

AIM: To compare the accuracy of capsule 13C-urea breath test (UBT) with conventional invasive methods for the diagnosis of Helicobacter pylori infection.METHODS: One hundred patients received CLO test,histological examination, culture and 100- or 50-mg capsule UBT for the diagnosis of Hpyloriinfection. Hpylori infection was defined as those with positive culture or positive results from both histology and CLO test.RESULTS: Both the sensitivity and specificity of the 100-mg capsule UBT (n = 50) were 100%. The sensitivity and specificity of the 50-mg capsule UBT (n = 50) were 96.4and 100%, respectively. Taken together, the accuracy of capsule UBT (n=100) was higher than that of CLO test,histology and culture (100% vs 92%, 91% and 89%,respectively; P= 0.035, 0.018 and 0.005, respectively). Our data showed that the optimal timing of sampling for 100-and 50-mg capsule UBT was 15-30 and 6-15 min, respectively.CONCLUSION: Capsule UBT has a higher accuracy compared with biopsy-based tests. It is an ideal method for the diagnosis of Hpyloriinfection.

Diagnostic accuracy of tests for Helicobacter pylori in an Alaska Native population

AIM： TO evaluate the accuracy of two non-invasive tests in a population of Alaska Native persons. High rates of Helicobacter pylori （H. pylon] infection, H. pyIori treatment failure, and gastric cancer in this population necessitate documentation of infection status at multiple time points over a patient＇s life.urease test, 13C urea breath test （UBT）, and immunoglobulin G antibodies to H. pylori in serum. The performances of 13C-UBT and antibody test were compared to a gold standard defined by a positive H. pylori test by culture or, in case of a negative culture result, by positive histology and a positive rapid urease test.RESULTS： The sensitivity and specificity of the 13C- UBT were 93% and 88%, respectively, relative to the gold standard. The antibody test had an equivalent sensitivity of 93% with a reduced specificity of 68%. The false positive results for the antibody test were associated with previous treatment for an H. pylorlinfection [relative risk （RR） = 2.8]. High levels of antibodies to H. py/or/were associated with chronic gastritis and male gender, while high scores in the 13C-UBT test were associated with older age and with theH. pylori bacteria load on histological examination （RR = 4.4）. CONCLUSION： The 13C-UBT outperformed the antibody test for H. pylori and could be used when a noninvasive test is clinically necessary to document treatment outcome or when monitoring for reinfection.

Hydrogen breath test for the diagnosis of lactose intolerance,is the routine sugar load the best one?

AIM: To evaluate the prevalence of lactose intolerance (LI) following a load of 12.5 g in patients diagnosed as high-grade malabsorbers using the hydrogen breath test (HBT)-25.METHODS: Ninety patients showing high-grade malabsorption at HBT-25 were submitted to a second HBT with a lactose load of 12.5 g.Peak hydrogen production,area under the curve of hydrogen excretion and occurrence of symptoms were recorded.RESULTS: Only 16 patients (17.77%) with positive HBT-25 proved positive at HBT-12.5.Hydrogen production was lower as compared to HBT-25 (peak value 21.55 parts per million (ppm) ± 29.54 SD vs 99.43 ppm ± 40.01 SD; P < 0.001).Symptoms were present in only 13 patients.The absence of symptoms during the high-dose test has a high negative predictive value (0.84) for a negative low-dose test.The presence of symptoms during the first test was not useful for predicting a positive low-dose test (positive predictive value 0.06-0.31).CONCLUSION: Most patients with a positive HBT-25 normally absorb a lower dose of lactose and a strict lactose restriction on the basis of a "standard" HBT is,in most instances,unnecessary.Thus,the 25 g lactose tolerance test should probably be substituted by the 12.5 g test in the diagnosis of LI,and in providing dietary guidelines to patients with suspected lactose malabsorption/intolerance.

Role of the^(13)C-methacetin breath test in the assessment of acute liver injury in a rat model

AIM: To evaluate the role of the 13C-methacetin breath test(13C-MBT) in the assessment of acute liver injury in a rat model.METHODS: Acute liver injury in rats was induced by a single intraperitoneal injection of D-galactosamine(D-GalN). Forty-eight male Sprague-Dawley rats were randomly assigned to a control group(n = 8) and five model groups(each n = 8), and acute liver injury was assessed at different time points(6, 12, 24, 48 and 72 h) after D-GalN injection. The 13C-MBT, biochemical tests, 15-min retention rate of indocyanine green(ICGR15), and liver biopsy were performed and compared between the control and model groups. Correlations between parameters of the 13C-MBT(Tmax, MVmax, CUM120 and DOBmax), biochemical tests, ICGR15 and liver necrosis score were also analyzed using Spearman'scorrelation analysis.RESULTS: Tmax, MVmax, CUM120 and DOBmax, as well as most of the traditional methods, correlated with the liver necrosis score(r = 0.493, P < 0.05; r =-0.731, P < 0.01; r =-0.618, P < 0.01; r =-0.592, P < 0.01, respectively). MVmax, CUM120 and DOBmax rapidly decreased and were lower than those in the controls as early as 6 h after D-GalN injection(3.84 ± 0.84 vs 5.06 ± 0.78, P < 0.01; 3.35 ± 0.72 vs 4.21 ± 1.44, P < 0.05; 52.3 ± 20.58 vs 75.1 ± 9.57, P < 0.05, respectively) and reached the lowest point 24 h after D-GalN injection. MVmax, CUM120 and DOBmax returned to normal levels 72 h after D-GalN injection and preceded most of the traditional methods, including liver biopsy.CONCLUSION: The 13C-MBT is a sensitive tool for the timely detection of acute liver injury and early prediction of recovery in a rat model. Further clinical studies are warranted to validate its role in patients with acute liver injury.

^(14)C-urea breath test in patients undergoing anti-tuberculosis therapy

AIM: Urea breath test (UBT) is a non-invasive diagnostic test for detecting the presence of Helicobacter pylori(H pylori).In this study we evaluated the effect of anti-tuberculosis therapy on the results of 14C-UBT.METHODS: Patients, with the diagnosis of tuberculosis (TB) who had a positive UBT at the point of starting antiTB therapy, were included. None had a history of peptic ulcer disease or had taken antibiotics, bismuth compounds and/or PPI in the previous month, 14C-UBT was repeated at the end of the second month and the end of treatment period and one month after completion of treatment course.RESULTS: Thirty-five patients (23 males) were enrolled.14C-UBT was negative in all 35 patients (100%) at the end of the second month and remained negative in 30cases (85.7%) at the end of the treatment course. One month after completion of treatment course, UBT remained negative in 13 patients (37.1%).CONCLUSION: Our report underscores the need for caution while interpreting urea breath test results in patients undergoing anti-TB therapy. Furthermore, the combination of drugs used in this study resulted in H pylori eradication in a minority of patients.