Correlation of lactulose-to-mannitol ratios in plasma and urine for intestinal permeability assessment in pigs.

OBJECTIVE: The lactulose-to-mannitol ratio test is a test to assess the disorders associated with gut permeability. The test requires an oral administration of the mixture of lactulose and mannitol and urine collection. The urinary ratio of lactulose to mannitol is an indicator of intestinal permeability. Due to the complexity of urine collection in animal studies, plasma exposure ratios of lactulose to mannitol compared to their urinary concentration ratios were evaluated following an oral administration of the sugar mixture in pigs. ANIMALS: 10 pigs were orally dosed with a solution of lactulose and mannitol mixture. PROCEDURES: Plasma samples were collected at predose, 10 and 30 minutes and 2, 4, and 6 hours postdosing, and cumulated urinary samples were collected at 6 hours for liquid chromatography-mass spectrometry analysis. The ratios of pharmacokinetic parameters of lactulose to mannitol and the plasma sugar ratios at a single time point or the mean values of several time points were compared to their urinary sugar ratios. RESULTS: The results revealed that the lactulose-to-mannitol ratios of AUC0-6h, AUCextrap, and Cmax were correlated to the urinary sugar ratios, and the plasma sugar ratios of a single time point at 2, 4, or 6 hours and the mean values of those time points were also appropriate to replace their urinary ratios in pigs. CLINICAL RELEVANCE: Following an oral administration of lactulose and mannitol mixture, blood collection, and assay can be an option for assessing intestinal permeability, especially in animal studies.

How is small bowel permeability in endometriosis patients? a case control pilot study.

Endometriosis is a chronic inflammatory disease of women of reproductive age. Small bowel (SB) permeability and lipopolysaccharides (LPS) could play a role in the perduration of low grade inflammation status and the pathogenesis of endometriosis. To clarify this hypothesis, we measured SB permeability through plasma values of LPS and urinary secretion of lactulose (La), mannitol (Ma) and their ratio (L/M) in patients with endometriosis compared with healthy controls (HC). Eight patients and 14 HC entered the study. SB permeability was evaluated by high-performance liquid chromatography of urine concentrations of La and Ma. Plasma levels of LPS were measured in the blood. Moreover, a nutritional, gastroenterological, quality of life evaluation was performed through validates questionnaires and complete gynaecological evaluations. The statistical analysis of the obtained data did not show differences in anthropometric and nutritional characteristics and gastrointestinal functional disease in the two groups. Patients reported higher levels of pelvic chronic pain (3.87 ± 2.99 vs 0.15 ± 0.55; pe = 0.001) and significantly higher LPS plasma levels (0.529 ± 0.11 vs 0.427 ± 0.08; p value = .027) than HC. Our results indicate that intestinal permeability is abnormal in endometriosis patients, and it might play a role in the pathogenesis of this chronic disease.

[Physiological effects, mechanisms of action and application of lactulose].

The discovery of lactulose as a bifidogenic factor became the background for the appearance of the prebiotics concept. Currently, lactulose is the most studied in terms of medical use oligosaccharide with a high prebiotic index. The exact mechanisms of action of lactulose remain largely unknown despite a number of new researches based on modern methods of molecular biology, genetics, and bioinformatics. The aim of this review to summarize and analyze the actual information about biological activity, probable mechanisms of action, and possible uses of lactulose in human nutrition. Results. The structure of lactulose, methods for its determination and preparation are briefly described. Promising methods for producing lactulose include enzymatic synthesis from lactose using ß-galactosidase or epimerase. Information on the physiological effects of lactulose and the mechanisms of its action on the human organism is presented. The works confirming the ability of lactulose to stimulate the growth of bifidobacteria and to influence the metabolism of the intestinal microbiota are summarized. The results of studies of the ability of lactulose to have antitoxic and anticarcinogenic effects are presented. The mechanisms of the positive effect of the prebiotic on the absorption of minerals, increased absorption of Ca and Mg in the human organism are described. The effect of lactulose on immunity and the possibility of its use to reduce the glucose blood level in patients with type 2 diabetes mellitus are shown. The main directions of the use of lactulose in food production are systematized. The data confirming the possibility of using lactulose as a growth factor for probiotics, as well as a protective agent to increase the survival of some starter cultures, are presented. Brief information on the doses and forms of lactulose apply in medicine is presented. The dependence of the effects of lactulose on the dose, health condition and age of patients has been established. Conclusion. Perspective directions of lactulose using in combination with probiotics, other prebiotics, and as an encapsulating ingredient for vitamins and other functional nutrition ingredients are determined. In this regard, the study of lactulose interaction with the components of complex products is relevant.

Measurement of intestinal permeability using lactulose and mannitol with conventional five hours and shortened two hours urine collection by two different methods: HPAE-PAD and LC-MSMS.

Urinary excretion of two orally-administered non-metabolizable sugars, lactulose and mannitol, is a valuable marker for evaluating intestinal permeability. Usually this test involves a time consuming procedure of about 5 hour's urine collection, which makes the test incompatible to some extent. As the results are expressed as the ratio of lactulose and mannitol recovered in urine within certain time, it may be possible to get similar result despite the reduced urine collection time of 2 hours. Moreover, different laboratories do the test by different methods, which make the results incomparable between laboratories. Here, we are also trying to find the correlation between results from most commonly used methods: HPAE-PAD and LC-MSMS. The lactulose: mannitol (LM) test was performed in a cohort of Bangladeshi infants considered at-risk for environmental enteropathy. 208 urine specimens from 104 (52 male and 52 female) infants were collected at 2 and 5 hours after LM solution administration and were tested for lactulose and mannitol by two different methods, one HPAE-PAD platform and another LC-MSMS platform. Median age of the children was 15.0 months (range 6.9 to 25.8 months) and their mean weight-for-age z-score was -0.92. A higher percentage of lactulose and mannitol recovery was found in 5 hours urine collection than in the corresponding 2 hours by both HPAE-PAD and LC-MSMS method, but when results were expressed as lactulose to mannitol ratio (LMR) there was no significant difference between 2 and 5 hours urine collection in both HPAE-PAD (P = 0.138) and LC-MSMS (P = 0.099) method. LMR based on 2 hours urine collection correlated well with LMR based on traditional 5 hours urine collection (Spearman's correlation coefficient 0.578 and 0.604 respectively for HPAE-PAD and LC-MSMS). In future, LM test to assess intestinal permeability in children can be simplified by shortening the urine collection time from 5 hours to 2 hours.

Additional Common Bean in the Diet of Malawian Children Does Not Affect Linear Growth, but Reduces Intestinal Permeability.

Background: Chronic malnutrition, as manifested by linear growth faltering, is pervasive among rural African children. Improvements in complementary feeding may decrease the burden of environmental enteric dysfunction (EED) and thus improve growth in children during the critical first 1000 d of development. Objective: We tested the hypothesis that systematically including common bean or cowpea into complementary feeding would reduce EED and growth faltering among children in rural Malawi. Methods: This was a double-blind clinical trial in which children 12-23 mo of age were randomly assigned to receive complementary feeding with 1 of 3 foods: roasted cowpea or common bean flour, or an isoenergetic amount of corn-soy blend as a control food for 48 wk. Children aged 12-23 mo received 155 kcal/d and thereafter until 35 mo received 200 kcal/d. The primary outcomes were change in length-for-age z score (LAZ) and improvements in a biomarker of EED, the percentage of lactulose (%L) excreted as part of the lactulose:mannitol dual-sugar absorption test. Anthropometric measurements and urinary %L excretion were compared between the 2 intervention groups and the control group separately with the use of linear mixed model analyses for repeated measures. Results: A total of 331 children completed the clinical trial. Compliance with the study interventions was excellent, with >90% of the intervention flour consumed as intended. No significant effects on LAZ, change in LAZ, or weight-for-length z score were observed due to either intervention legume, compared to the control. %L was reduced with common bean consumption (effect estimate was -0.07 percentage points of lactulose, P = 0.0007). The lactulose:mannitol test was not affected by the legume intervention. Conclusion: The addition of common bean to complementary feeding of rural Malawian children during the second year of life led to an improvement in a biomarker of gut health, although this did not directly translate into improved linear growth. This trial was registered at clinicaltrials.gov as NCT02472301.

Endurance Exercise Increases Intestinal Uptake of the Peanut Allergen Ara h 6 after Peanut Consumption in Humans.

Controlled studies on the effect of exercise on intestinal uptake of protein are scarce and underlying mechanisms largely unclear. We studied the uptake of the major allergen Ara h 6 following peanut consumption in an exercise model and compared this with changes in markers of intestinal permeability and integrity. Ten overnight-fasted healthy non-allergic men (n = 4) and women (n = 6) (23 ± 4 years) ingested 100 g of peanuts together with a lactulose/rhamnose (L/R) solution, followed by rest or by 60 min cycling at 70% of their maximal workload. Significantly higher, though variable, levels of Ara h 6 in serum were found during exercise compared to rest (Peak p = 0.03; area under the curve p = 0.006), with individual fold changes ranging from no increase to an increase of over 150-fold in the uptake of Ara h 6. Similarly, uptake of lactulose (2-18 fold change, p = 0.0009) and L/R ratios (0.4-7.9 fold change, p = 0.04) were significantly increased which indicates an increase in intestinal permeability. Intestinal permeability and uptake of Ara h 6 were strongly correlated (r = 0.77, p < 0.0001 for lactulose and Ara h 6). Endurance exercise after consumption may lead to increased paracellular intestinal uptake of food proteins.

Human small intestine is capable of restoring barrier function after short ischemic periods.

AIM: To assess intestinal barrier function during human intestinal ischemia and reperfusion (IR). METHODS: In a human experimental model, 6 cm of jejunum was selectively exposed to 30 min of ischemia (I) followed by 30 and 120 min of reperfusion (R). A sham procedure was also performed. Blood and tissue was sampled at all-time points. Functional barrier function was assessed using dual-sugar absorption tests with lactulose (L) and rhamnose (R). Plasma concentrations of citrulline, an amino acid described as marker for enterocyte function were measured as marker of metabolic enterocytes restoration. Damage to the epithelial lining was assessed by immunohistochemistry for tight junctions (TJs), by plasma marker for enterocytes damage (I-FABP) and analyzed by electron microscopy (EM) using lanthanum nitrate as an electrondense marker. RESULTS: Plasma L/R ratio's were significantly increased after 30 min of ischemia (30I) followed by 30 min of reperfusion (30R) compared to control (0.75 ± 0.10 vs 0.20 ± 0.09, P < 0.05). At 120 min of reperfusion (120R), ratio's normalized (0.17 ± 0.06) and were not significantly different from control. Plasma levels of I-FABP correlated with plasma L/R ratios measured at the same time points (correlation: 0.467, P < 0.01). TJs staining shows distortion of staining at 30I. An intact lining of TJs was again observed at 30I120R. Electron microscopy analysis revealed disrupted TJs after 30I with paracellular leakage of lanthanum nitrate, which restored after 30I120R. Furthermore, citrulline concentrations closely paralleled the histological perturbations during intestinal IR. CONCLUSION: This study directly correlates histological data with intestinal permeability tests, revealing that the human gut has the ability of to withstand short episodes of ischemia, with morphological and functional recovery of the intestinal barrier within 120 min of reperfusion.

A Canadian Study toward Changing Local Practice in the Diagnosis of Pediatric Celiac Disease.

Background. The European Society for Pediatric Gastroenterology, Hepatology and Nutrition endorses serological diagnosis (SD) for pediatric celiac disease (CD). The objective of this study was to pilot SD and to prospectively evaluate gastrointestinal permeability and mucosal inflammation at diagnosis and after one year on the gluten-free diet (GFD). We hypothesized that SD would be associated with similar short term outcomes as ED. Method. Children, 3-17 years of age, referred for possible CD were eligible for SD given aTTG level ≥200 U/mL, confirmed by repeat aTTG and HLA haplotypes. Gastrointestinal permeability, assessed using sugar probes, and inflammation, assessed using fecal calprotectin (FC), at baseline and after one year on a GFD were compared to patients who had ED. Results. Enrolled SD (n = 40) and ED (n = 48) patients had similar demographics. ED and SD groups were not different in baseline lactulose: mannitol ratio (L : M) (0.049 versus 0.034; p = 0.07), fractional excretion of sucrose (%FES; 0.086 versus 0.092; p = 0.44), or fecal calprotectin (FC; 89.6 versus 51.4; p = 0.05). At follow-up, urine permeability improved and was similar between groups, L : M (0.022 versus 0.025; p = 0.55) and %FES (0.040 versus 0.047; p = 0.87) (p > 0.05). FC improved but remained higher in the SD group (37.1 versus 15.9; p = 0.04). Conclusion. Patients on the GFD showed improved intestinal permeability and mucosal inflammation regardless of diagnostic strategy. This prospective study supports that children diagnosed by SD have resolving mucosal disease early after commencing a GFD.

Randomized Clinical Trial of Preoperative Feeding to Evaluate Intestinal Barrier Function in Neonates Requiring Cardiac Surgery.

OBJECTIVES: To evaluate intestinal barrier function in neonates undergoing cardiac surgery using lactulose/mannitol (L/M) ratio measurements, and to determine correlations with early breast milk feeding. STUDY DESIGN: This was a single-center, prospective, randomized pilot study of 27 term-born neonates (≥ 37 weeks gestation) requiring cardiac surgery who were randomized to 1 of 2 preoperative feeding groups: nil per os (NPO) or trophic (10 mL/kg/day) breast milk feeds. At 3 time points (preoperative [preop], postoperative [postop] day 7, and postop day 14), subjects were administered an oral L/M solution, after which urine L/M ratios were measured using gas chromatography, with higher ratios indicative of increased intestinal permeability. Trends over time in the mean urine L/M ratios for each group were estimated using a general linear mixed model. RESULTS: There were no adverse events related to preoperative trophic feeding. In the NPO group (n = 13), the mean urine L/M ratio was 0.06 at preop, 0.12 at postop day 7, and 0.17 at postop day 14. In the trophic breast milk feeds group (n = 14), the mean urine L/M ratio was 0.09 at preop, 0.19 at postop day 7, and 0.15 at postop day 14. In both groups, L/M ratios were significantly higher at postop day 7 and postop day 14 compared with preop (P < .05). CONCLUSION: Neonates have increased intestinal permeability after cardiac surgery extending to at least postop day 14. This pilot study was not powered to detect differences in benefit or adverse events comparing the NPO and trophic breast milk feeds groups. Further studies to identify mechanisms of intestinal injury and therapeutic interventions are warranted. TRIAL REGISTRATION: Registered with ClinicalTrials.gov: NCT01475357.

Differential trafficking of saccharidic probes following aspirin in clinical tests of intestinal permeability in young healthy women.

The effects of inflammatory changes on the absorption of different-sized probes and their permeability ratios are poorly understood. The aim of the present study was to determine the effects of a pharmacological agent on the permeability of the gut mucosa to saccharidic probes of larger and smaller molecular weight. Permeability was assessed by half-hourly urinary excretion of a combined dose of d-mannitol, l-rhamnose and lactulose following consumption of a single 600 mg dose of aspirin and compared with a placebo in a cross-over study in 20 healthy female volunteers. The temporal patterns of excretion of all probes were bimodal, being best fitted by polynomial functions. The relatively small early peak was evident for at least 4 h for smaller sugars, but was less evident with lactulose, being overshadowed by a larger second peak. These conclusions were further supported by separate analyses of the segments of the temporal plots between 2.5 and 4 h and between 4.5 and 6 h. The forms of these curves did not change significantly following dosing with aspirin. A greater proportion of the total dose of mannitol than rhamnose was excreted over the collection period. Following the consumption of aspirin, the cumulative rate of excretion of the smaller sugars (i.e. mannitol and rhamnose) was significantly reduced whereas that of lactulose was increased over the 6 h collection period. Aspirin has opposite effects on the absorption of larger and smaller probes, influencing the outcome of the test. These results have important consequences for the design and comparison of clinical tests of permeability.

Intestinal permeability in subjects from two different race groups with diverse stone-risk profiles.

It is well established that calcium oxalate stones may be caused by colonic or ileum oxalate (Ox) hyperabsorption (secondary to intestinal dysfunction). Studies have reported that increased intestinal permeability (IP) can cause hyperabsorption of nutrients culminating in passive diffusion of Ox. In South Africa, renal stones occur in the white population (W) but are extremely rare in the black population (B). Previous studies have shown that despite B having a hyperoxalurogenic diet relative to W, urinary Ox in the former is not higher. It has been suggested that different Ox handling mechanisms in the groups are the cause of this disparity. The present study was undertaken to examine whether the IP index, a reliable and accurate measure of intestinal integrity, plays a role in this anomaly. Ten healthy males from each group ingested a dual-sugar isotonic solution containing 5 g lactulose (LA) and 2 g mannitol (MA). IP was assessed by comparing the LA:MA ratio in 5 h urine samples using high performance anion exchange chromatography coupled with pulse amperometric detection to measure the concentration of each sugar. 24 h dietary intake and urine composition were also determined. LA excretion was identical in both groups (0.03 %) while MA excretion was 8.3 % in B and 11.3 % in W. IP index was 0.004 for B and 0.003 for W. It is concluded that IP is not a contributory factor in the apparent different handling of dietary Ox in B and W South Africans. It is speculated that differences in renal transporters may play a role.

Semiquantitative assessment of breath hydrogen testing.

BACKGROUND AND AIM: A major use of breath hydrogen testing is to assess absorptive capacity for sugars to assist dietary design for management of gut symptoms. Qualitative reporting takes no account of the vigor of hydrogen response and provides little insight into degrees of malabsorption. This study aimed to describe a semiquantitative reporting method and to compare results with those reported qualitatively. METHODS: In consecutive Caucasian patients with Crohn's disease (n = 87), ulcerative colitis (59), functional gastrointestinal disorders (FGID) (162), and healthy controls (76), area under the curve was calculated for lactulose (15 g). This was compared with that for lactose (50 g) and fructose (35 g). Degree of malabsorption was categorized into arbitrary groups. RESULTS: Semiquantitative results for ≥ 30% (designated "convincing") malabsorption was most similar to those using a qualitative cutoff value of 20 ppm, but in 38% and 21% of patients, the classification of malabsorption (nil or clinically significant) changed for fructose and lactose, respectively. Using a cutoff of 10 ppm, 49% and 5% were classified differently. Crohn's disease had a higher prevalence (42%) of convincing fructose malabsorption than controls (24%) or patients with FGID (33%) (P < 0.02). Highest prevalence of convincing lactose malabsorption (38%) was in ulcerative colitis, greater than controls (18%) and FGID (18%) (P < 0.02). CONCLUSIONS: Semiquantitative assessment provides different results with different clinical implications in more than one third of patients, but disease-related alterations in prevalence are similar to those defined qualitatively. This method may be preferable because it lessens the confounding influence of the vigor of the hydrogen response.

Intestinal permeability in normally nourished and malnourished children with and without diarrhea.

We evaluated the association between diarrhea, malnutrition and intestinal function using the lactulose-mannitol test. Our study showed that a third of all children have abnormal intestinal permeability, there was an expected increase of permeability in children with acute diarrhea and alteration in intestinal permeability was greater in children with concurrent malnutrition and diarrhea.

Lactulose breath test to assess oro-cecal transit delay and estimate esophageal dysmotility in scleroderma patients.

OBJECTIVES: To assess the correlation between delayed oro-cecal transit time (OCTT) and esophageal motility abnormalities in a cohort of systemic sclerosis (SSc) patients. METHODS: We prospectively enrolled 50 consecutive SSc patients and 60 healthy volunteers (HVs) as controls. Both groups underwent glucose breath test (GBT) to exclude small intestine bacterial overgrowth, lactulose hydrogen, and octanoic acid breath tests (LHBT and OBT) to measure OCTT and gastric emptying (GE), respectively, and manometry to assess esophageal motility. RESULTS: Thirty-one (63%) SSc patients presented ineffective esophageal motility (IEM) compared with 3 HVs (5%; P<0.01), 37 (74%) had an abnormal OCTT compared with 4 HVs (7%; P <0.01), and 16 (32%) had an altered GE compared with 4 HVs (7%; P <0.01). The median OCTT and gastric t½ were longer in SSc than in HVs (165 min vs. 101 min and 125 min vs. 78 min, respectively; P <0.01). A delayed GE was present in 12/37 (32%), whereas IEM in 27/37 (73%) SSc patients with prolonged OCTT. The prevalence of IEM increased in parallel with the prolongation of OCTT (31% when OCTT<150 min, 73% when OCTT≥150 min, and up to 85% when OCTT>180 min, P<0.01). CONCLUSIONS: Abnormalities of both esophageal and small intestine motility are frequent in SSc patients and esophageal motility is altered in most cases with small bowel involvement. Delayed GE plays a limited role in prolonging OCTT. LHBT is a non-invasive, cheap, well-tolerated diagnostic tool that may be useful to estimate intestinal involvement and also to estimate a higher risk of esophageal hypomotility in SSc patients.

Novel multi-sugar assay for site-specific gastrointestinal permeability analysis: a randomized controlled crossover trial.

BACKGROUND & AIMS: Increased gastrointestinal (GI) permeability is an important hallmark of many conditions, potentially leading to antigen exposure and sepsis. Current permeability tests are hampered by analytical limitations. This study aims to compare the accuracy of our multi-sugar (MS) and the classical dual sugar (DS) test for detection of increased GI permeability. METHODS: Ten volunteers received permeability analysis using MS (1 g sucrose, lactulose, sucralose, erythritol, 0.5 g rhamnose in water) or DS (5 g lactulose, 0.5 g rhamnose), after indomethacin or placebo. Blood and urine were analyzed by isocratic LC-MS. RESULTS: MS testing revealed significantly elevated urinary lactulose/rhamnose (L/R) ratios after indomethacin, due to enhanced lactulose excretion (P < .01) and unaltered rhamnose excretion. The DS test showed increased L/R ratios, due to increased lactulose excretion and decreased rhamnose excretion (both P < .05). After indomethacin, plasma L/R increased in both assays (P < .05 and P < .01). Urinary and plasma L/R ratios correlated significantly. Indomethacin increased sucrose excretion and 0-1 h sucrose/rhamnose. Colon permeability was unchanged. CONCLUSIONS: Sensitive permeability analysis is feasible in plasma and urine using MS or DS test. In contrast to the DS test, monosaccharide excretion is not decreased by the MS test. In short, the MS test provides accurate, site-specific information on gastroduodenal, small, and large intestinal permeability. Registered at US National Library of Medicine (http://www.clinicaltrials.gov, NCT00943345).

Meta-analysis of oro-cecal transit time in fasting subjects.

PURPOSE: Computer simulations are utilized during pharmaceutical development in order to design appropriate formulation based on the absorption, distribution, metabolism, and excretion (ADME) and physicochemical properties of target compounds, so that adequate prescriptions are offered to patients. Oro-cecal transit time (OCTT) is an important factor affecting these simulations because the absorption of drug that administered orally and the resultant pharmacokinetic profile are expressed as a function of time. Given the large intra- and inter-individual variance in OCTT, it is unsurprising that an accurate model has not yet been proposed. METHODS: We conducted a meta-analysis using subject-level data to construct a statistical model that predicted OCTT. Literature that utilized lactulose to measure OCTT was identified and analyzed using a mixed-effects model. RESULTS: The OCTTs of fasting healthy subjects were expressed using a linear model, with the amount of lactulose as the single significant explanatory factor. We found that this model could statistically distinguish the OCTTs of subjects with altered physical status from those of healthy people. Specifically, cystic fibrosis and celiac disease most significantly affected OCTT. CONCLUSION: The OCTT models developed herein incorporate inter-subject variations and can contribute to providing more accurate predictions of drug pharmacokinetic profiles.

Modern approach for determination of lactulose, mannitol and sucrose in human urine using HPLC-MS/MS for the studies of intestinal and upper digestive tract permeability.

A new analytical procedure was described for the simultaneous determination of lactulose, mannitol and sucrose in urine, in which HILIC chromatography and tandem mass spectrometry detection are used. Sugars are orally administered for the estimation of intestinal permeability in children digestive tract. Samples were purified by dispersive solid phase extraction (d-SPE) using Amberlite MB150 resin. Raffinose was selected as an internal standard. The chosen chromatographic separation was carried out on ZIC(®)-HILIC column in 10 min at a flow rate of 0.3 mL/min, using mixture of acetonitrile (ACN) and ammonium acetate (NH(4)Ac) in water (H(2)O) as the mobile phase. Within-run precision (CV) measured at three concentrations was 1.08%, 0.32% and 0.49% for lactulose; 1.88%, 0.47% and 0.75% for mannitol, 2.95%, 1.31% and 0.6% for sucrose. Between-run CVs were 0.75%, 1.1% and 1.2% for lactulose; 1.1%, 1.02% and 1.01% for mannitol; 1.17%, 1.4% and 1.05% for sucrose. Analytical recovery of all three sugar probes was 95.06-99.92%. The detection limits were: 15.94 ng/mL for lactulose, 17.10 ng/mL for sucrose and 11.48 ng/mL for mannitol. The proposed method is rapid, simple, sensitive and suitable for the determination of intestinal permeability of the sugar derivatives in children.

The effect of aspirin and smoking on urinary excretion profiles of lactulose and mannitol in young women: toward a dynamic, aspirin augmented, test of gut mucosal permeability.

BACKGROUND: We explored the temporal dynamics of the lactulose mannitol test and the influence of a single dose of aspirin. METHODS: Twenty healthy female volunteers each received 600 mg aspirin or placebo in random sequence and were subsequently dosed with 10 g lactulose and 5 g mannitol, their urine collected every half hour for 6h. KEY RESULTS: The lactulose:mannitol ratios (LMR) of urine samples collected over the entire 6-h period were significantly higher than those collected in the first 3 h. Greater quantities of mannitol were excreted over the first than the subsequent 3 h. A similar pattern of temporal variation in mannitol excretion was found in smokers and non-smokers and was maintained following administration of a single 600 mg dose of aspirin. The rates at which lactulose was excreted were relatively constant over the entire 6 h period of collection, but mean levels were increased over the entire 6 h following the administration of aspirin. The effect of aspirin did not differ significantly between smokers and non-smokers. CONCLUSIONS & INFERENCES: While the LMR test is sufficiently sensitive to reproducibly detect the increase in intestinal permeability resulting from a single 600 mg oral dose of aspirin, the temporal patterns of excretion of mannitol and lactulose differ both in the presence and absence of aspirin. Hence, variation in sampling period and in method of dosage are likely to influence the result and it is preferable to examine the patterns of absorption of component sugars separately with due regard to the method of dosage.

Assessment of intestinal permeability using sugar probes: influence of urinary volume.

BACKGROUND: As the accuracy of the "Sugar Test" is currently debated, this study was conducted to focus on how urine volumes may impact the test results. METHODS: Fifty-five subjects, 23 healthy and 32 with Irritable Bowel Syndrome (IBS), were enrolled. Lactulose and D-mannitol dissolved in water were administered to all the participating subjects; the urine excreted was collected and the total urine volume was measured. The urine samples were analyzed by High Performance Liquid Chromatography (HPLC). The results were expressed as percentage of urine recovery of lactulose and D-mannitol and lactulose/D-mannitol ratio (LMR). RESULTS: All subjects were divided into two groups: subjects with urine volume < 500 mL and subjects with urine volume > or = 500 mL. Urine analysis showed that the mean LMR was significantly lower in subjects with urine volume > or = 500 mL than in subjects with urine volume < 500 mL (0.02 +/- 0.02 vs 0.04 +/- 0.04; p < 0.05). A significant increase in D-mannitol recovery was found to be associated with greater urine volumes (p < 0.001). CONCLUSIONS: The urine volume may influence urinary excretion of sugar probes. Intake of liquids should therefore be carefully monitored before and during the test and the volume of urine produced over the period of collection should be precisely measured.

Effects of timing, sex, and age on site-specific gastrointestinal permeability testing in children and adults.

OBJECTIVES: Measurement of gastrointestinal (GI) permeability is commonly used in research and often used clinically. Despite its utility, little is known about sugar excretion timeframes or the potential effects of age and sex on GI permeability testing. We seek to determine the timeframes of sugar excretion and the potential effects of age and sex on urinary recovery of the sugars. SUBJECTS AND METHODS: Healthy adults (n = 17) and children (n = 15) fasted 4 hours after the evening meal and then ingested a solution of sucrose, lactulose, mannitol, and sucralose. Urine was collected at 30, 60, and 90 minutes after ingestion and then each time the subjects voided during the next 24 hours. Each urine void was collected separately. RESULTS: Median age for the adults was 47.5 years (range 21-57 years) and for children 10 years (range 5-17 years). There were no differences between children and adults in mean percent dose of sugar recovered. The time of peak urinary recovery of the sugars was generally similar between children and adults. Sucrose urinary recovery declined with age (P = 0.008; r2 = 0.19) unrelated to sex. Lactulose and sucralose urinary recovery declined with age in females (P = 0.05, r2 = 0.24 and P = 0.011, r2 = 0.41; respectively) but not in males. CONCLUSIONS: Overall, sugar urinary recovery is comparable in children and adults. Specific sugar urinary recovery may change as a function of age and/or sex. These results need to be taken into account when planning and interpreting gastrointestinal permeability studies.