Intestinal permeability after single dose gluten challenge in coeliac disease

The changes of intestinal permeability before and after a gluten load were studied. The study group comprised 27 patients with coeliac disease (mean age 12.3 years) and 19 healthy controls matched by sex and age. Intestinal permeability was studied by measuring the urinary excretion of two sugars, lactulose and L-rhamnose, before and six hours after the ingestion of five palatable biscuits made with 50 g of gluten powder. The patients with coeliac disease had been on a gluten free diet during the previous two years. After the gluten load lactulose and L-rhamnose urinary excretion changed significantly in patients, and a significant increase in the lactulose: L-rhamnose ratio was also observed. No significant changes were observed in the controls. In view of the modification of the three biopsies diagnostic protocol made by the European Society for Paediatric Gastroenterology and Nutrition, permeability tests associated with single gluten challenges may be an added contribution to the accuracy of the diagnosis in childhood.

A human Lactobacillus strain (Lactobacillus casei sp strain GG) promotes recovery from acute diarrhea in children

To determine the effect of a human Lactobacillus strain (Lactobacillus casei sp strain GG, Gefilac) on recovery from acute diarrhea (82% rotavirus), 71 well-nourished children between 4 and 45 months of age were studied. After oral rehydration, the patients randomly received either Lactobacillus GG-fermented milk product, 125 g (10(10-11) colony-forming units) twice daily (group 1); Lactobacillus GG freeze-dried powder, one dose (10(10-11) colony-forming units) twice daily (group 2); or a placebo, a pasteurized yogurt (group 3) 125 g twice daily; each diet was given for 5 days, in addition to normal full diet otherwise free of fermented dairy products. The mean (SD) duration of diarrhea after commencing the therapy was significantly shorter in group 1 (1.4 [0.8] days) and in group 2 (1.4 [0.8] days) than in group 3 (2.4 [1.1] days); F = 8.70, P less than 0.001. After rehydration, each dietary group maintained a positive weight trend. The urinary lactulose-mannitol recovery ratios (means [95% confidence intervals]) on admission were 0.09 (0.03, 0.24) in group 1, 0.12 (0.07, 0.22) in group 2, and 0.08 (0.04, 0.18) in group 3; no significant alterations in intestinal permeability were observed at retesting after 2 days of realimentation. The result indicates that early nutritional repletion after rehydration causes no mucosal disruption and is beneficial for recovery from diarrhea. It is further suggested that Lactobacillus GG in the form of fermented milk or freeze-dried powder is effective in shortening the course of acute diarrhea.

Aggressive chemotherapy for acute leukaemia frequently causes intestinal protein leakage

Cytostatic drugs are known to produce disturbances in intestinal absorption of carbohydrates. To further explore the gastrointestinal (GI) toxicity of cytostatic therapy, 37 patients with acute leukemia were investigated during and/or after remission induction courses by the use of the differential sugar absorption test (DSAT) and the intestinal clearance of alpha-1-antitrypsin (ClAAT). The ratio of the lactulose to the mannitol excretion in the urine was found abnormal in 44% of the tests. The ClAAT was increased in 74% of tests. The tests results differed considerably from patient to patient and depended on the chemotherapy course; correlation between the tests was low, probably indicating the unrelated pathophysiological processes were measured. After haematological regeneration, abnormal test results normalised. It is concluded that aggressive chemotherapy not only causes a reduction in the absorption of sugars, but commonly also protein leakage. These GI side-effects are reversible, and the application of both tests in combination provides a practical and reproducible method for investigation of GI toxicity in patients treated with cytostatic drugs.

A pilot study of fluticasone propionate in untreated coeliac disease

Although gluten withdrawal is likely to remain the mainstay of treatment for adult coeliac disease, many patients find the diet inconvenient and unpalatable and compliance among asymptomatic patients is often poor. Oral corticosteroids have been used for patients who seem to be resistant to gluten withdrawal but preparations with low systemic bioavailability might be preferable. We have given a new glucocorticoid (fluticasone propionate) to 12 adults with untreated coeliac disease for six weeks while they were on a normal diet. One patient defaulted and one suffered a relapse in a pre-existing neoplasm. Excluding these, there was an improvement of symptoms, a mean weight gain of 2 kg, and a rise in albumin of 5.4 g/l. There was a significant improvement in the lactulose/mannitol excretion ratio (p less than 0.05) and in all histological variables examined in paired biopsy specimens (surface and crypt intraepithelial lymphocyte/enterocyte and goblet cell/enterocyte ratios and enterocyte height, p less than 0.01 or better). In six paired specimens sucrase and alkaline phosphatase activity increased in all (p less than 0.05) and lactase in five of six. No appreciable side effects were observed, but two patients had suppressed cortisol values and synacthen responses at six weeks. A further three, with normal pretrial results, had a blunted tetracosactrin response at six weeks. Fluticasone propionate seems worthy of further assessment in the treatment of coeliac disease as an adjunct to gluten withdrawal.

Do non-steroidal anti-inflammatory drugs increase colonic permeability?

Urinary excretion of orally administered lactulose and 51 chromium labelled ethylenediamine tetra-acetate (51Cr-EDTA) was measured in 12 healthy adult subjects and in six patients with ileostomies to assess intestinal permeability. In normal subjects, 24 hour urinary recovery of 51Cr-EDTA was significantly greater than that of lactulose (mean (SEM) 2.27 (0.15) v 0.50 (0.08)% oral dose; p less than 0.001), but in ileostomy patients recovery of the two markers was the same. In normal subjects, therefore, the difference between the two markers may arise from bacterial break-down of lactulose but not of 51Cr-EDTA in the distal bowel, urinary excretion of lactulose representing small intestinal permeation and that of 51Cr-EDTA representing both small and large intestinal permeation. The markers were then given simultaneously to nine patients receiving non-steroidal anti-inflammatory drugs (NSAIDs) for rheumatoid arthritis and osteoarthritis. The 24 hour urinary recovery of 51Cr-EDTA in the patients was significantly greater than normal (4.64 (1.20) v 2.27 (0.15)% oral dose; p less than 0.01), but that of lactulose was not significantly affected. Moreover, the increase in 51Cr-EDTA recovery was most noticeable in the later urine collections. Both of these findings suggest that NSAIDs may increase colonic permeability.

Alterations of intestinal permeability to sugars in infants following neonatal surgery

The 12-h urinary elimination of orally ingested mannitol and lactulose was studied in 29 infants aged 3 days-20 months admitted in an intensive care unit of gastrointestinal surgery, and in 24 age-matched healthy controls. In patients with short bowel syndrome, there was a significant fourfold reduction in urinary mannitol elimination compared with controls. The lactulose/mannitol urinary ratio was significantly increased in patients with necrotizing enterocolitis (p less than 0.01) and in patients with disorders of intestinal propulsion during episodes of diarrhea with a monomorphic fecal flora (p less than 0.01). The urinary recovery of mannitol and lactulose after oral loads is a good marker of intestinal mucosal damage in infants with surgical disorders of the digestive tract.

Rapid and simultaneous determination of lactulose and mannitol in urine, by HPLC with pulsed amperometric detection, for use in studies of intestinal permeability

The lactulose/mannitol dual sugar absorption test is a non-invasive test of intestinal permeability. Its widespread use has been limited by the difficulties of analysis for carbohydrates in urine at low concentrations. We describe a "high-pressure" liquid-chromatographic method for determining lactulose and mannitol in urine, in which anion-exchange chromatography and pulsed amperometric detection are used. Sample preparation is simple and fast, and lactulose and mannitol and the internal standards arabinose and cellobiose are well resolved within 15 min. Analytical response of the method is linear with concentrations to 3 g/L, and one can detect as little as 0.3 mg of lactulose per liter of urine. Analytical recovery was between 90% and 107% for all sugars analyzed, and there was good agreement with results by a gas-chromatographic method (r = 0.993 lactulose, 0.984 mannitol). The method may potentially be applied to the study of other carbohydrates present in biological fluids at low concentrations.

Intestinal permeability is increased in burn patients shortly after injury

There is increasing direct experimental and indirect clinical evidence to indicate that under certain conditions intestinal barrier function may be lost in trauma victims. No direct measurements, however, have been performed in patients to determine whether intestinal permeability is increased shortly after a major thermal injury in the absence of infection. Fifteen hemodynamically stable burn patients with burns on more than 20% of their body surface (39% +/- 12%) had their intestinal permeability measured within 24 hours of injury with use of the two nonmetabolizable sugars lactulose and mannitol as permeability markers. Lactulose absorption was fourfold higher in the patients (223 +/- 54 mumol) than in the controls (58 +/- 11 mumole; p less than 0.02), whereas the lactulose/mannitol ratio was threefold higher (5.2 vs 1.7; p less than 0.05). Thus intestinal permeability was increased in patients with moderate to major burn injuries shortly after injury.

Automated enzymatic assays for the determination of intestinal permeability probes in urine. 1. Lactulose and lactose

Lactulose is becoming the disaccharide of choice in the dual sugar assessment of passive permeability of the small intestinal mucosa. However its more widespread use is hampered by current analytical methods which are tedious and time consuming. An automated spectrophotometric technique for the assay of this sugar in urine is presented in which lactulose is linked by a series of enzyme reactions to the equimolar production of NADPH. In addition to lactulose, the procedure also gives accurate values for lactose, glucose and fructose in the urine sample. The assay has been shown to be highly specific for lactulose and lactose and was not affected by high concentrations of other sugars or other urinary constituents. Within assay and between assay precision were similar with the coefficient of variation for both sugars in the range 0.4-1.6%. The technique represents a significant improvement in time, simplicity and precision on existing methods of analysis.

Intestinal permeability as a measure of small intestinal mucosal integrity: correlation with jejunal biopsy

The permeability of the small intestine was measured and jejunal biopsy performed in 39 children with gastrointestinal disorders. Intestinal permeability was measured using orally administered mannitol and lactulose as probe molecules in an isotonic solution (274 mOs/l), and the results were expressed as the ratio of the urinary excretion of the two sugars over 5 h. Urine samples were analysed for mannitol and lactulose content by high performance liquid chromatography. Children with small intestinal mucosal damage, irrespective of the cause, had a significantly lower (P less than 0.001) mannitol excretion (mean recovery 1.21% of ingested dose) than those with a normal mucosa (mean recovery 5.3%), while lactulose excretion did not differ (P greater than 0.05). The mean value of the lactulose:mannitol urinary excretion ratios was significantly higher (P less than 0.001) in subjects with an abnormal mucosa (0.98) compared to those with a normal mucosa (0.2). Using the mean plus two standard deviations of the normal mucosa group to define the upper limit of normal, all lactulose: mannitol excretion ratios from the abnormal mucosa group were above this limit. The results of this study show that the sugar permeability test is a sensitive, non-invasive screening test for jejunal mucosal damage in children and shows good correlation with jejunal biopsy results.

Effects of anthracycline therapy on intestinal absorption in patients with advanced breast cancer

Although cytotoxic chemotherapy for human cancer has been reported to induce alterations in intestinal permeability, its effects on the absorptive process are still controversial. We have studied mediated and nonmediated absorption in 10 patients with metastatic breast cancer before and after treatment with Adriamycin by the use of specific test sugars given orally and their subsequent urinary recovery, as measured by chromatography. Mediated absorption was investigated by the use of D-xylose and 3-O-methylglucose, while lactulose and L-rhamnose were used to study nonmediated permeation. Lactulose is considered a marker of unmediated paracellular (tight junction) permeation, while L-rhamnose explores passage across cell membranes. The test was performed on patients before and on the second and the eighth days after Adriamycin administration, and only once in 22 age-matched healthy women. Under basal conditions, as well as 2 and 8 days after chemotherapy, D-xylose and 3-O-methylglucose absorption was 35% lower in patients than in controls (P less than 0.001). Lactulose absorption was significantly higher in patients than in controls under basal conditions (P less than 0.001); it reached levels three times higher the second day after chemotherapy, and returned to basal levels by the eighth day. The data suggest an early reversible effect of Adriamycin on cellular tight junctions with resulting increased permeabilization. This effect seems of a toxic nature rather than due to increased cell loss. It is interesting that both nonmediated absorption and mediated absorption were already altered before chemotherapy in cancer patients, suggesting a preexisting functional damage of the intestine. The significance of this alteration as a potential mechanism of cancer cachexia is discussed.

Intestinal permeability in Crohn's disease

Crohn's disease may present insidiously, especially in childhood, and diagnosis may be delayed. In addition, the clinical assessment of the extent of disease activity may be inaccurate. Using mannitol and lactulose as probe molecules we have carried out a cross sectional study of intestinal permeability in patients with active Crohn's disease (n = 17) and control subjects (n = 31). Activity was assessed by an activity index score. The lactulose:mannitol urinary excretion ratio was significantly increased in Crohn's disease. Overall sensitivity was 82%, and 92% when activity was moderate or severe. When permeability was compared with the activity index there was a significant correlation among patients. In five patients studied longitudinally a significant correlation was also present. Measurement of intestinal permeability is non-invasive, and may be useful both as a screening test in patients with non-specific symptoms, and for the assessment of the extent of disease activity in patients with Crohn's disease.

Lactulose/mannitol test: an ideal screen for celiac disease

A lactulose/mannitol (La/Ma) test was compared with a standard cellobiose/mannitol test (Ce/Ma) in 17 patients with newly diagnosed celiac disease and 12 healthy controls. The mean La/Ma test was 0.163 (SEM 0.076) in celiacs and 0.016 (SEM 0.002) in controls. The mean Ce/Ma test was 0.132 (SEM 0.024) in celiacs and 0.014 (SEM 0.002) in controls (p less than 0.001). There is no significant difference between the new La/Ma test and the Ce/Ma test. Eighty-two patients referred to a general gastroenterology clinic with symptoms or signs of celiac disease performed a La/Ma test. A jejunal biopsy was indicated in 44 of these. In this selected group the sensitivity was 89%, specificity 54%, and negative predictive value of 95%. The La/Ma test fulfills the criteria of a screening test; it is sensitive, of low cost, and simple to perform, and it has the advantage of a simple enzyme assay and does not cause diarrhea in patients with hypolactasia. It can, therefore, be used in screening large patient populations.

Intestinal permeability in patients with atopic eczema

Passive intestinal permeability was measured in 15 adult patients with atopic eczema. Values in the patients did not differ significantly from those in 12 healthy control subjects. These results suggest that altered intestinal permeability is not important in the pathogenesis of atopic eczema in adults.

A single dose of endotoxin increases intestinal permeability in healthy humans

To investigate the effects of endotoxin on gut barrier function, we performed paired studies of intestinal permeability in healthy humans (N = 12) receiving intravenous Escherichia coli endotoxin (4 ng/kg) or 0.9% saline solution. Two nonmetabolizable sugars, lactulose and mannitol, which are standard permeability markers, were administered orally, 30 minutes before and 120 minutes after the test injection. The 12-hour urinary excretion of these substances after endotoxin/saline solution administration was used to quantitate intestinal permeability. After endotoxin administration systemic absorption and excretion of lactulose increased almost two-fold (mean +/- SEM, 263 +/- 36 mumol per 12 hours vs 145 +/- 19 mumol per 12 hours during saline studies). Similar but less marked alterations in mannitol absorption and excretion occurred after endotoxin injection (5.7 +/- 0.3 mmol per 12 hours vs 4.9 +/- 0.3 mmol per 12 hours). When individual 12-hour lactulose excretion after endotoxin administration was related to the magnitude of systemic responses, a significant relationship occurred between lactulose excretion and elaboration of norepinephrine and between lactulose excretion and minimum white blood cell count. These data suggest that a brief exposure to circulating endotoxin increases the permeability of the normal gut. These observations are consistent with the hypothesis that during critical illness, prolonged or repeated exposure to systemic endotoxins or associated cytokines may significantly compromise the integrity of the gastrointestinal mucosal barrier.

Increased intestinal permeability associated with infection in burn patients

Thermal injury may be associated with disruption of normal gut barrier integrity. To test this hypothesis, we assessed intestinal permeability with the nonmetabolizable, poorly absorbed disaccharide lactulose, which is efficiently excluded by the normal intestinal mucosa. Permeability studies were performed in 15 burned patients (aged 18 to 67 years; mean burn size, 40%) and 11 healthy controls. Lactulose, 10 g, was administered enterally, together with 5 g of mannitol as a control, and urinary excretion rates were determined. Lactulose excretion and the lactulose/mannitol excretion ratio increased threefold (160 +/- 30 vs 57 +/- 7 mumol and 0.113 +/- 0.033 vs 0.035 +/- 0.005) in the infected patients (sepsis score, 10 +/- 2; burn size, 38% +/- 6%). In contrast, noninfected burn patients (sepsis score, 0) had permeability values similar to those of controls (66 +/- 10 mumol and 0.036 +/- 0.007). Permeability increased as the severity of infection increased. Infection in burn patients is associated with increased bowel permeability. The intestine may be a primary source of sepsis. Alternatively, the systemic response to infection may alter gut barrier function, which could facilitate translocation of bacteria and absorption of endotoxin.

Urinary mannitol: lactulose excretion ratios and jejunal mucosal structure

A dual sugar (mannitol, lactulose) absorption test was evaluated using an iso-osmolar oral dose in two groups of children: a study group of 43 children divided into five subgroups, based on severity of mucosal damage, and a control group of 53 children with histologically normal jejunal biopsy specimens. After an oral dose, the three hour urinary mannitol: lactulose ratios in the control group showed a highly significant positive correlation with body surface area. After correction for the body surface area relationship, a control lower limit was defined by the mean -2SD of the log10 transformed control mannitol: lactulose ratios. Specificity and sensitivity for severe villous atrophy was 98% and 95% respectively but the sensitivity declined rapidly with decreasing degrees of mucosal damage, and the test would not therefore be an adequate screening procedure for all enteropathies. In sequential studies in 18 children, the changes in the mannitol: lactulose ratio were consistent with the changes in mucosal structure induced by gluten challenge or gluten withdrawal. The test may therefore have a role in any sequential study of lesions of the mucosa of the small intestine.

The effect of hyperthermia and radiation on small bowel permeability using 51Cr EDTA and 14C mannitol in man

A prospective study was conducted to study the effect of radiotherapy (RT) and regional pelvic hyperthermia (HT) on intestinal permeability in three groups of patients. Fifteen acted as cancer controls, receiving RT away from the peritoneal cavity, 21 patients received radical pelvic or abdominopelvic RT and 13 patients pelvic RT followed by pelvic HT using a BSD 1000 phased array applicator. Small bowel permeability was measured by oral administration of a mixture of [51Cr]EDTA, [14C]mannitol and lactulose before and after a course of treatment. The absorption of each marker was calculated by measuring the urinary excretion over 0-6 and 0-12 hours. The 6 hour collection gave results similar to the 12 hour collection, but had logistical advantages. The EDTA absorption rose and the mannitol absorption fell during a course of treatment, but the best index of permeability change was the EDTA/mannitol ratio (E/M). The E/M ratio rose by a factor of 2.4 (P less than 0.001) and 1.82 (P = 0.05) following RT and RT/HT respectively. There was no significant difference between the RT and RT/HT groups but the thermal dose to the RT/HT group was low (23 min./equiv 43 degrees C over three or four fractions in 4 weeks). There was no correlation between small bowel permeability and bowel frequency. The E/M permeability test is a useful simple functional assay for assessing small bowel damage after RT and RT/HT.

The impact of milk and weaning diet on gastrointestinal permeability in English and Gambian infants

To test the hypothesis that cow's milk formula and weaning diet may damage the gut mucosa, the gastrointestinal permeability of 77 healthy English and Gambian infants was measured from the urinary recovery of the markers lactulose and mannitol included in feeds. All infants were born at term and studied at 6, 12 and 18 weeks of age. No infant developed diarrhoea or failed to thrive. Infants fed on cow's milk formula had higher urinary lactulose: mannitol excretion ratios than breast-fed infants at 6 weeks of life (P less than 0.05). There was no significant difference in the urinary marker excretion ratios of English formula-fed and Gambian breast-fed infants at 12 weeks. An increase in urinary lactulose: mannitol excretion ratios was seen in all infants at 18 weeks. This was more probably due to increasing age than to the introduction of weaning diet. Cow's milk formula feeding was associated with greater intestinal permeability than breast feeding in infants aged 6 weeks. The introduction of weaning diet after 6 weeks did not appear to have an impact on the gastrointestinal permeability of healthy growing infants born in either England or rural Gambia.

Oral chenodeoxycholic acid increases small intestinal permeability to lactulose in humans

In animals, chenodeoxyholic acid (chenodiol) causes significant small intestinal mucosal injury which is paralleled by increased intestinal permeability. The objective of this study was to determine whether chenodiol increases small intestinal mucosal permeability in humans. This was assessed in a before-after trial by collecting urine from nine fasted healthy male volunteers for 3 h after oral intake of an isotonic solution containing 1 g mannitol, 5 g L-rhamnose and 10 g lactulose, all nondigestible sugars. After at least 72 h, this was repeated 1 h after taking 750 mg of chenodiol orally. The amount of each sugar excreted in the urine was quantified by high performance liquid chromatography. Chenodiol doubled the percent urinary excretion of lactulose from 0.21 +/- 0.12 (SD) to 0.42% +/- 0.25 (p less than 0.02) and the ratio of lactulose to mannitol or to rhamnose [0.012 +/- 0.005 to 0.027 +/- 0.013 (p less than 0.01) and 0.045 +/- 0.022 to 0.087 +/- 0.039 (p less than 0.05), respectively]. Oral administration of 750 mg chenodiol is associated with increased small intestinal permeability to lactulose in humans, supporting the possibility that this drug may also cause acute small intestinal mucosal injury.

Assessment of the lactulose-mannitol test in Crohn's disease

The mannitol-lactulose intestinal permeability test was evaluated in 100 healthy controls and 47 patients with Crohn's disease. These patients were further separated into three subgroups of increased activity (Harvey-Bradshaw index) and in two subgroups, with elective colonic lesions and associated ileal and colonic lesions. Results were given as percentages of urinary recoveries for mannitol (M), lactulose (L), and L/M ratio. As a whole, patients with Crohn's disease have lower mean M and higher mean L and mean L/M ratios than controls. The magnitude of alterations in M, L, and L/M increased with activity. The sensitivity of the test, however, reached interesting figures (67%:L and 86%:L/M) only in subgroup III which was composed of relapsing patients. Mean M was lower in patients with associated ileal lesion but, whatever the criterion (M, L, or L/M), the test does not provide any clue for the detection of a possible infraclinical associated ileal localisation.

Does 'sugar' permeability reflect macromolecular absorption? A comparison of the gastro-intestinal uptake of lactulose and beta-lactoglobulin in the neonatal guinea pig

Intestinal closure to cow's milk beta-lactoglobulin occurs within 6 days of birth in the guinea pig. Passive intestinal permeability to lactulose persists through the suckling period. The uptake of small water-soluble markers does not reflect macromolecular absorption, and has no place in the measurement of immunologic protein handling by the gut.

Toxic effect on the rat small intestine of chronic administration of asbestos in drinking water

Sprague-Dawley rats were given a 0.5 g/l Chrysotile asbestos solution in their drinking water (approximately 7 mg/day ingested) for 1.5 years and compared to control rats of the same age. During this time there were no differences in weight or appearance of the asbestos-treated rats in comparison to controls maintained under the same conditions. However, when in vivo intestinal permeability studies were performed using a gavage/urinary collection technique, some significant changes were noted. The recovery of lactulose in the urine of asbestos-treated rats was 0.66 +/- 0.07%, significantly less than that of the controls (1.01 +/- 0.08, P less than 0.005). The recovery of mannitol was similarly decreased (2.2 +/- 0.28 vs. 3.0 +/- 0.17, P less than 0.02), but that of rhamnose was unchanged. Creatinine clearance studies indicated that there was no impairment of kidney function in the asbestos-treated group and polarized light microscopy did not reveal any asbestos fibers in sections of the small bowel. The results suggest that the chronic exposure of rats to asbestos fibers in the drinking water results in a decreased ability of the intestine to absorb some non-metabolizable sugars.

[Measurement of intestinal permeability to sugars: application in the diagnosis of celiac disease and cow's milk protein enteropathy]

Intestinal permeability to macromolecules was studied by measuring differential urinary elimination of two orally ingested non-metabolizable sugars of different molecular size, mannitol and lactulose. In 25 control children, mannitol and lactulose urinary elimination were 16.30 +/- 5.77% and 0.33 +/- 0.10% of ingested dose, respectively, with a mean lactulose/mannitol (M/M) urinary ratio of 2.73 +/- 0.70%. In 7 celiac children, L/M ratio exhibited a significant rise: 8.53 +/- 2.54% (p less than 0.001). In 7 children with cow's milk sensitive enteropathy under exclusion diet, L/M ratio was normal in fasting condition: 2.63 +/- 1.28% and raised significantly during provocation test with milk: 7.22 +/- 3.88% (p less than 0.01). Intestinal permeability test is a reliable index of villous atrophy and cow's milk sensitive enteropathy.