Comparison of the one-gramd-[14C]xylose breath test to the [14C]bile acid breath test in patients with small-intestine bacterial overgrowth

In twelve patients with culture-proven bacterial overgrowth of the small intestine, the ability of a newly-developed one-gramd-[¹⁴C]xylose breath test to detect bacterial overgrowth was compared to that of the [¹⁴C]bile acid breath test. All patients manifested excessive production of breath¹⁴CO₂ after the administration of one gram [¹⁴C]xylose, with 83% of the patients being abnormal within the first hour of testing. In contrast, during the [¹⁴C]bile acid breath test, four of the twelve patients had no period of excessive¹⁴CO₂ production (above the 95% confidence range of controls). Nutrient malabsorption (fat, cobalamin, xylose) was seen with both true-positive and false-negative bile acid breath tests. The one gram [¹⁴C]xylose breath test, utilizing a substrate with more predominant absorption in the proximal small intestine and which can be catabolized by Gram-negative aerobic bacteria, appears to have a greater degree of sensitivity and specificity than the bile acid breath test in detecting the presence of small-intestine bacterial overgrowth.Dr. King is the recipient of a Research Associate Award from the Veterans Administration. During the performance of these studies Dr. Toskes was the recipient of a Clinical Investigator Award from the Veterans Administration.Supported in part by Grant #RR-82 from the National Institutes of Health.     

Comparison of the 1-gram [14C]xylose, 10-gram lactulose-H2, and 80-gram glucose-H2 breath tests in patients with small intestine bacterial overgrowth

The sensitivity of three breath tests (1-g [14C]xylose, 10-g lactulose-H2, and 80-g glucose-H2) was studied in 20 subjects with culture-documented small intestine bacterial overgrowth. Elevated breath 14CO2 levels were seen within 30 min of [14C]xylose administration in 19 of 20 subjects with bacterial overgrowth and 0 of 10 controls. In contrast, H2 breath tests demonstrated uninterpretable tests (absence of H2-generating bacteria) in 2 of 20 subjects with bacterial overgrowth and 1 of 10 controls and nondiagnostic increases in H2 production in 3 of 18 glucose-H2 and 7 of 18 lactulose-H2 breath tests in subjects with bacterial overgrowth. These findings demonstrate continued excellent reliability of the 1-g [14C]xylose breath test as a diagnostic test for bacterial overgrowth, indicate inadequate sensitivity of H2 breath tests in detecting bacterial overgrowth, and suggest the need for evaluation of a 13CO2 breath test having the same characteristics as the [14C]xylose test (avidly absorbed substrate having minimal contact with the colonic flora) for nonradioactive breath detection of bacterial overgrowth in children and reproductive-age women.     

Limitations of indirect methods of estimating small bowel transit in man

Experiments were carried out in healthy volunteers to explore the utility of a new [14C]lactulose breath test for measuring small intestinal transit time in man and to use this procedure to test whether two antidiarrheal agents, codeine and clonidine, alter small intestinal transit time during digestion of a liquid meal. In an initial validation study performed in 12 subjects (three studies in each subject), a liquid test meal containing 10 g [14C]lactulose was administered and the colonic entry time estimated from the time course of 14CO2 excretion in breath compared with that of H2 excretion. There was a fair correlation (r = 0.77; P less than 0.001) between results obtained by the two methods; both methods gave similar results, but 14CO2 output was delayed when compared to H2 output and was incomplete. The meal also contained xylose and [13C]glycine, permitting the duodenal entry time of the meal to be estimated by the appearance of xylose in blood and 13CO2 in breath, respectively. The same liquid meal was then used to examine the effect on small intestinal transit time (colonic entry time minus duodenal entry time) of codeine or clonidine. 99Tc-sulphur colloid was also added to the meal to permit a comparison of small intestinal transit estimated by imaging with that estimated by the 14CO2-lactulose breath test. 99Tc radioactivity appeared in the cecum (as assessed using gamma scintigraphy) about 2 hr before 14CO2 radioactivity appeared in breath; the correlation between transit time estimated by the two methods was moderate (r = 0.61; P less than 0.05). Based on the [14C]lactulose data, small intestinal transit time ranged from less than 1 to 3 hr for a liquid meal containing 10 g lactulose; within-subject variation (coefficient of variation 17%) was considerably less than between-subject variation (coefficient of variation 56%). Codeine increased the small intestinal transit time significantly (from 2.7 +/- 0.3 hr to 5.0 +/- 0.9 hr; mean +/- SE), whereas clonidine did not alter small intestinal transit time, as estimated by the colonic entry time minus duodenal entry time. Neither drug influenced duodenal entry time. These results suggest that the [14C]lactulose breath test, which has only moderate accuracy, may have occasional utility as a convenient, noninvasive method for estimating small intestinal transit time in man. However, this study also suggests that indirect methods of estimating small bowel transit in man have limitations, variability, and possibly may lack the desired sensitivity.     

Lactulose hydrogen and [14C]xylose breath tests in patients with ileoanal anastomosis

To study the intestinal bacterial flora and mouth to pouch transit time after ileoanal anastomosis, lactulose hydrogen and [¹⁴C]xylose breath tests were performed on 19 patients with ileoanal anastomosis and J-pouch and 8 patients with conventional ileostomy. Evaluated by the [¹⁴C]xylose breath test, patients with ileoanal anastomosis and ileal pouch showed no difference in the bacterial flora of the proximal small bowel when compared with ileostomy patients. The lactulose hydrogen breath test showed a significant rise in breath hydrogen, indicating bacterial overgrowth, in 68% of patients with ileoanal anastomosis but in none with conventional ileostomy (p<0.01). It was concluded that this peak in breath hydrogen was produced by the bacteria in the pouch. Thus the lactulose hydrogen breath test can be used to measure mouth to pouch transit time in 2/3 of patients with ileoanal anastomosis. Mouth to pouch transit time was 63±9 min and it correlated inversely with stool frequency (p<0.05).

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Résumé Pour étudier la flore intestinale bactérienne et le temps de transit bucco-anal après anastomose iléo-anale des tests respiratoires au lactulose hydrogène C14 xylose ont été réalisés chez 19 patients avec anastomose iléoanale et poche en J et chez 8 malades avec une iléostomie conventionnelle. Lors du test C14 xylose il n'y avait aucune différence en ce qui concerne la flore bactérienne de l'intestin grèle proximal chez les malades qui avaient une anastomose iléo-anale avec poche et chez ceux qui avaient une iléostomie. Le test au lactulose hydrogène montrait une augmentation significative de l'hydrogène respiratoire indiquant une pullulation bactérienne chez 68% des malades avec anastomose iléo-anale mais chez aucun de ceux qui avaient une iléostomie conventionnelle (p<0.01). On conclue que le pic d'hydrogène respiratoire était produit par les bactéries dans la poche. Ainsi le test au lactulose hydrogène respiratoire peut être usé pour mesurer le temps de transit bouche-poche chez 2/3 des patients avec une anastomose iléo-anale. Le temps de transit bouche-poche était de 63±9 mn et était corrélé inversement avec la fréquence des selles (p<0.05).

     

Glucose Malabsorption Associated with Rapid Intestinal Transit

Twenty-five patients with chronic diarrhea were studied with a combined glucose-hydrogen breath test (GHBT) and nuclear transit scan to elucidate the role of abnormal transit in the pathogenesis of diarrhea. Eight of the 25 patients demonstrated both a rapid orocecal transit time by nuclear scan (less than 30 min) and a positive hydrogen breath test (greater than 20 ppm increase in H2 after a 50-g glucose challenge). Because these individuals had no anatomic abnormalities predisposing to small bowel bacterial overgrowth, it is probable that they demonstrated colonic bacterial metabolism of carbohydrate secondary to glucose malabsorption associated with rapid small bowel transit. The eight patients exhibited some form of autonomic dysfunction generally related to systemic disease. Thus, there may be a subset of patients with chronic diarrhea related to rapid intestinal transit. A combined GHBT-nuclear transit scan permits accurate identification of such individuals and improves the accuracy of hydrogen breath tests in the diagnosis of bacterial overgrowth.     

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

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

Use of the lactose-[13C]ureide breath test for diagnosis of small bowel bacterial overgrowth: comparison to the glucose hydrogen breath test

Purpose  

The glucose hydrogen breath test (GHBT) is commonly used as a noninvasive test to diagnose small bowel bacterial overgrowth (SBBO) but its validity has been questioned. Our aim was to evaluate the lactose-[¹³C]ureide breath test (LUBT) to diagnose SBBO and to compare it with the GHBT, using cultures of intestinal aspirates as a gold standard.     

The diagnosis of small bowel bacterial overgrowth in elderly patients.

OBJECTIVE: To examine the frequency of small bowel bacterial overgrowth in elderly subjects. DESIGN: Prospective observational study. SETTING: Department of Health Care of the Elderly in a university teaching hospital. PATIENTS: Thirteen elderly control subjects having undergone normal gastroscopy with normal hematology and anthropometry; 39 consecutive referrals of elderly patients with clinical or biochemical evidence of malnutrition. MAIN OUTCOME MEASURES: Duodenal bacterial counts and the 14C-glycocholate, hydrogen, and 14C-xylose breath tests. RESULTS: Five of the 13 control subjects and 21 of 39 patients with malnutrition had high duodenal bacterial counts (greater than 10(5) organisms/mL), whereas only seven patients were judged to have clinically significant bacterial overgrowth. The 14C-xylose breath test showed a high specificity (89%) but a low sensitivity (30%) when compared with the results of duodenal culture. The hydrogen breath tests and the 14C-glycocholate test showed a similar picture of moderately high specificity and low sensitivity (77% and 20%, respectively, for the hydrogen breath test, 76% and 33%, respectively, for the 14C-glycocholate test). CONCLUSIONS: A positive xylose breath test was the best predictor of high duodenal bacterial counts. However, since many elderly subjects have high duodenal bacterial counts, the overdiagnosis of bacterial overgrowth syndrome will result if duodenal culture is relied upon exclusively.     

Small-bowel bacterial overgrowth in elderly people: clinical significance and response to treatment.

Duodenal-jejunal bacterial overgrowth is increasingly recognized in old age but its clinical significance is poorly defined. In this study, 16 elderly subjects were selected on the basis of an abnormal lactulose breath hydrogen test from a series of 27 in whom there was some reason to suspect malabsorption. In 12 of these 16 cases, pentagastrin tests showed normal gastric acid secretion and in 12 cases the small bowel was radiologically normal. Nutritional assessment, anthropometric measurements, culture of small-bowel aspirates, 14C-triolein breath tests and blood xylose tests were performed before and after 4 to 6 months of cyclical antibiotic therapy. Initially all patients except two showed evidence of malabsorption. After antibiotic treatment alone, 13 patients gained in weight and body fat. There were significant rises in the mean levels of haemoglobin, serum protein and calcium. Blood xylose test levels increased in 14 cases, reaching normal in all except one, whereas 14C-triolein excretion also increased in 14 and reached normal in 12 out of 16 cases. The breath hydrogen test reverted to normal in all cases and bacterial overgrowth was eliminated in 10 out of 11. The mouth-to-caecum transit time was prolonged initially (mean 190 min) and was unaffected by therapy (mean 196 min). Malabsorption and undernutrition are significant features of small-bowel overgrowth in the elderly and can be specifically corrected by antibiotic treatment. The clinical effect can be equally severe in elderly patients with or without an anatomical defect of the small bowel.(ABSTRACT TRUNCATED AT 250 WORDS)     

Reduced Accuracy of 14C-D-Xylose Breath Test for Detecting Bacterial Overgrowth in Gastrointestinal Motility Disorders

The accuracy of the ¹⁴C-D-xylose breath test in the diagnosis of small-bowel bacterial overgrowth was prospectively evaluated in 10 patients with motility disorders: 6 myopathic, 3 neuropathic, and 1 mechanical obstruction. Six of the 10 patients had small-bowel bacterial overgrowth (≥10⁵ colony-forming units/ml) on culture of small-bowel aspirate. Increased breath ¹⁴CO₂ levels were documented in three of six patients with positive cultures and in two of four with negative cultures. Two patients with positive results by both methods and one of two patients with positive breath ^l4CO₂ but negative cultures had previously undergone gastric surgery. Three patients with myopathic dysmotility had positive cultures but negative breath tests. Cultures of duodenal aspirates and the D-xylose test had sensitivities of 80% and 40%, respectively, for the finding of hypoalbuminemia. Compared with cultures, the sensitivity and specificity of the breath test were 60% and 40%, respectively. Impaired delivery of ^l4C-D-xylose for bacterial metabolism may result from postprandial antral hypomotility (n = 4) or low-amplitude (n = 6) small-bowel motility, contributing to the false-negative breath tests. Thus, culture is the optimal method to detect small-bowel bacterial overgrowth in patients with motility disorders.     

Eradication of small intestinal bacterial overgrowth reduces symptoms of irritable bowel syndrome

OBJECTIVES: Irritable bowel syndrome is the most common gastrointestinal diagnosis. The symptoms of irritable bowel syndrome are similar to those of small intestinal bacterial overgrowth. The purpose of this study was to test whether overgrowth is associated with irritable bowel syndrome and whether treatment of overgrowth reduces their intestinal complaints. METHODS: Two hundred two subjects in a prospective database of subjects referred from the community undergoing a lactulose hydrogen breath test for assessment of overgrowth were Rome I criteria positive for irritable bowel syndrome. They were treated with open label antibiotics after positive breath test. Subjects returning for follow-up breath test to confirm eradication of overgrowth were also assessed. Subjects with inflammatory bowel disease, abdominal surgery, or subjects demonstrating rapid transit were excluded. Baseline and after treatment symptoms were rated on visual analog scales for bloating, diarrhea, abdominal pain, defecation relief, mucous, sensation of incomplete evacuation, straining, and urgency. Subjects were blinded to their breath test results until completion of the questionnaire. RESULTS: Of 202 irritable bowel syndrome patients, 157 (78%) had overgrowth. Of these, 47 had follow-up testing. Twenty-five of 47 follow-up subjects had eradication of small intestinal bacterial overgrowth. Comparison of those that eradicated to those that failed to eradicate revealed an improvement in irritable bowel syndrome symptoms with diarrhea and abdominal pain being statistically significant after Bonferroni correction (p < 0.05). Furthermore, 48% of eradicated subjects no longer met Rome criteria (chi2 = 12.0, p < 0.001). No difference was seen if eradication was not successful. CONCLUSIONS: Small intestinal bacterial overgrowth is associated with irritable bowel syndrome. Eradication of the overgrowth eliminates irritable bowel syndrome by study criteria in 48% of subjects.     

Urinary Choloyl-PABA Excretion in Diagnosing Small Intestinal Bacterial Overgrowth

The synthetic substrate cholyl-PABA, developed by conjugating cholic acid with paraaminobenzoic acid, is hydrolyzed by the bacterial enzyme cholyl hydrolase to release free PABA. This study aimed to evaluate whether quantitating urinary excretion of PABA after oral administration of cholyl-PABA can detect small intestinal bacterial overgrowth. In the first phase, investigations were performed on 10 healthy volunteers to study the dynamics of urinary excretion of PABA and any adverse reactions after oral administration of 1.2 g of cholyl-PABA. Another 10 healthy volunteers and 25 adult patients with various gastrointestinal disorders participated in the second phase, where the urinary cholyl-PABA test was compared to the [¹⁴C]xylose breath test (XBT). The upper limit of normal levels of urinary PABA excretion at the end of 4 h was 1.1% of the administered dose of cholyl-PABA. The urinary PABA excretion after 4 hr [median (range), in percentage] in the XBT-positive group was 1.6 (0.6–35.0), which was significantly higher than those in the XBT-negative group [0.7 (0.4–1.8)] and the healthy controls [0.7 (0.2–1.1)]. The agreement between the XBT and the urinary cholyl-PABA test was 85.7% (P < 0.01). No adverse effect was noted. In conclusion, the urinary cholyl-PABA test offers a simple, safe, noninvasive, and rapid method for diagnosing small intestinal bacterial overgrowth and warrants further clinical evaluation.     

Etiology of portal hypertension may influence gastrointestinal transit

Background: Gastrointestinal transit studies have shown contradictory results in patients with portal hypertension. We have studied gastric emptying, small‐bowel transit and colonic transit in patients with portal hypertension. The association between small‐bowel bacterial overgrowth and gastrointestinal transit was assessed. Methods: Sixteen patients (6 females) with portal hypertension and esophageal varices were included. A newly developed radiological procedure was used to measure gastrointestinal transit during one visit. Variceal pressure was measured and culture of small‐bowel aspirate was used to diagnose small‐bowel bacterial overgrowth. The results were compared to results obtained in 83 healthy subjects. Results: Half gastric emptying time in male patients was 3.8 (0.9–5.8)?h versus 2.5 (0.4–4.0)?h in healthy males (median and percentile 10–90; P?P?Conclusion: Etiology of liver disease and gender may influence transit in patients with portal hypertension. Small‐bowel bacterial overgrowth was associated with delayed small‐bowel transit.     

Diagnostische Evaluation der D��nndarmmotilit?t

Investigations of small bowel motility are performed relatively infrequently partly because of impaired accessibility of the small bowel. For diagnostic evaluation transit measurements and manometric techniques are generally available. Scintigraphy is regarded as the reference method for evaluation of small bowel transit but is rarely performed in Europe. Clinically, the lactulose hydrogen breath test is most frequently used for estimation of orocecal transit time. Apart from this radiological techniques can be used to roughly estimate small bowel transit. Capsule techniques and the lactulose-¹³C-ureide breath test represent potential alternatives. In contrast to transit measurements small bowel manometry reveals information on the contractile patterns of the small bowel and thus on pathophysiological mechanisms. However, small bowel manometry is relatively complex and labor-intensive and is therefore reserved for special indications and specialized centres.     

Simultaneous measurement of gastric emptying, small bowel residence and colonic filling of a solid meal by the use of the gamma camera

A method for determining the profiles of gastric emptying, small intestinal residence, and colonic filling of a solid test meal, labelled with 250 microCi 99mTechnetium sulphur colloid has been evaluated in nine healthy volunteers and six patients with a disturbance in bowel habit. Mean small bowel transit time was determined by deconvolving the rate of colonic filling with the rate of gastric emptying. In normal subjects, the stomach appeared to empty exponentially with a half time of 1.2 +/- 0.3 hours (mean +/- SD). Food reached the colon by 2.8 +/- 1.5 hours. The mean small bowel transit time was 4.0 +/- 1.4 hours. In most normal subjects, the colon appeared to fill in a linear fashion with approximately 16% food residues entering every hour, and the profile of colonic filling in normal subjects was similar to the profile of ileal emptying observed after feeding a similar radiolabelled solid meal to 14 patients equipped with terminal ileostomies. There was a highly significant correlation between the onset of breath hydrogen excretion and the appearance of radioactivity over the caecum (r = 0.88, p less than 0.01), though in one third of subjects the increase in caecal radioactivity preceded the rise in breath hydrogen concentration by more than 20 minutes. There was also a highly significant correlation between the mean transit time and values for colonic filling but not values for gastric emptying. Patients with irritable bowel syndrome who had diarrhoea tended towards short small bowel transit and early colonic filling, whereas patients who have constipation tended towards long small bowel transit and delayed colonic filling. This method offers a novel means of assessing small bowel transit time, small bowel residence and the profile of colonic filling in man.     

Gastrointestinal transit times of radiolabeled meal in progressive systemic sclerosis

Gastrointestinal transit times were measured in 12 patients with progressive systemic sclerosis. The CREST syndrome (calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, and teleangiectasia) was found in all patients. None of the patients reported complaints referable to specific gastric, small intestinal, or colonic involvement. The patient group had an increased mean gastric emptying time of^99mTc-labeled cellulose fiber when compared with 16 healthy controls {1.17 (0.89–1.38) hr [median (range)] vs 0.84 (0.56–1.88) hr; P<0.02}, whereas mean gastric emptying time of 2– to 3-mm¹¹¹In-labeled plastic particles was unaffected [1.86 (0.99–2.74) hr vs 1.50 (0.92–2.51) hr; NS]. No difference was observed in mean small intestinal transit time of cellulose fiber [4.33 (0.50–7.04) hr vs 3.74 (2.09–7.59) hr; NS] or plastic particles [4.21 (2.00–6.25) hr vs 3.53 (1.50–6.70) hr; NS] between patients and controls. The patient group had an increased mean colonic transit time of plastic particles [47 (24–116) hr vs 29 (18–46) hr; P<0.01]. These findings suggest that asymptomatic delay in gastric emptying and colonic transit is frequent in patients with progressive systemic sclerosis.This work was supported by the Danish Hospital Foundation for Medical Research; Region of Copenhagen, The Faroe Islands, and Greenland.     

COBALAMIN DEFICIENCY and SMALL BOWEL BACTERIAL OVERGROWTH: A COMMON ASSOCIATION

Background  Bacterial overgrowth may cause cobalamin deficiency through competition for dietary cobalamin in the small intestine. The objective of this study was to prospectively determine the prevalence of small bowel bacterial overgrowth in patients with documented cobalamin deficiency in a tertiary referral centre.
Methods  Patients identified with cobalamin deficiency underwent diagnostic investigations including: Endoscopy (with gastric antrum, gastric body and duodenal biopsies and duodenal aspirate), ¹⁴C-D-Xylose breath test, intrinsic factor antibody, anti-endomysial antibody and red cell folate level. 'Definite' small bowel bacterial overgrowth was defined as either a positive ¹⁴C-D-Xylose breath test or > 100 000 CFU/mL of culture of duodenal aspirate. 'Suspected' small bowel bacterial overgrowth was defined as an elevated red cell folate in the absence of supplemental folate therapy.
Results  Over a 2-year period, 62 patients with cobalamin deficiency were identified, of whom, 26 (42%) had 'definite' small bowel bacterial overgrowth, whilst a further nine (15%) had 'suspected' small bowel bacterial overgrowth. Nineteen (31%) had pernicious anaemia, and no cause for cobalamin deficiency could be found in eight (13%) patients. The diagnosis found in the remaining patients included coeliac disease (4), Crohn's Disease (1), gastric resection (2), vegan (2), homozygotes of the MTHFR gene (C677T) mutation (2), and one had enteropathy associated with common variable immunodeficiency (CVID). 'Definite' small bowel bacterial overgrowth was found to coexist with nine of the 19 cases of pernicious anaemia, two coeliac subjects, one CVID enteropathy and one patient with the MTHFR gene mutation.
Conclusion  Small bowel bacterial overgrowth is commonly associated with cobalamin deficiency.     

Non-invasive methods for assessing the small intestines

Non-invasive methods investigating small bowel functions are critically reviewed. For intestinal absorption, we discuss the value of fecal fat determination, D-xylose testing and breath tests. Intestinal bacterial overgrowth may be assessed by breath hydrogen test or 14C-D-Xylose breath test. Small intestinal transit time can be measured by a scintigraphy method or by a breath hydrogen technique. Intestinal clearance of alpha-1 antitrypsin is now the method of choice for the detection of protein-losing enteropathy. Intestinal permeability can be assessed by 51Cr-EDTA/14C-mannitol ratio or PEG 900 method.     

d-Xylose absorption test

Thed-xylose absorption test has been used during the last four decades for evaluation of malabsorption in the small intestine. However, some disagreement still exists about the recommended method of performing this test the 1-hr blood test, the 5-hr urine test, or both. We evaluated the test by performing 125 combined blood and urine tests in 111 patients. Normal xylose absorption was recorded in both blood and urine in 71 tests (group A, 56.8%). Abnormal test results in both blood and urine were recorded in 29 patients (group B, 23.2%). Only one patient had a pathological blood value and normal xylose excretion in the urine. Twenty-four patients (group D, 19.2%) had normal 1-hr blood xylose (>25 mg/100 ml) with abnormal 5-hr urine xylose (<4.5 g/5 hr). Fat and/or bile salt malabsorption were documented in 21 patients (87.5%) of this group using stool fat analysis and the [¹⁴C]cholylglycine breath test. These data suggest that in adults the 5-hr urine collection more accurately reflects intestinal absorption in comparison with the 1-hr blood value.     

Appraisal of the 14C-glycocholate acid test with special reference to the measurement of faecal 14C excretion

The ¹⁴C-glycocholate test, including the measurement of marker corrected faecal ¹⁴C, has been assessed in the following groups of subjects: normal controls (18), patients with diarrhoea not attributable to altered bile acid metabolism (21), patients with diverticula of the small intestine (12), patients with previous resection of ileum and often proximal colon (34), and established ileostomists (10). Patients with diverticular disease had increased breath ¹⁴CO₂ excretion, but normal faecal excretion of ¹⁴C, and this test was more frequently abnormal than the Schilling test. Ileostomists excreted increased amounts of faecal ¹⁴C, even when the ileum was intact and apparently normal. The pattern after resection was complex. Breath ¹⁴C output was normal if the ileal resection was less than 25 cm in length, although some of these patients had increased faecal ¹⁴C excretion if, in addition, at least 15 cm of proximal colon had been resected or by-passed. Longer ileal resections were associated with increased breath and/or faecal ¹⁴C excretion, depending in part on the length of colon resected or by-passed and the 24 hour faecal volume. Fewer than half these patients had both increased breath and faecal excretion of isotope and faecal ¹⁴C alone was occasionally normal with an ileal resection of 50 cm of more. The ¹⁴C-glycocholate test was more frequently abnormal than the Schilling test in this group. The use of faecal marker correction had only a minor impact on the results. These data suggest that, in patients with ileal resection, faecal ¹⁴C, like faecal weight, is determined by the extent of colonic resection as well as by the amount of ileum resected.