Follow-up of celiac disease with D-xylose breath test

13C-xylose and 14C-xylose breath tests for the diagnosis of coeliac disease

OBJECTIVES

Xylose absorption testing has traditionally involved measurement of serum xylose and/or measurement of excreted xylose in urine. However, by enriching xylose with a 13C- or 14C-isotope, absorption of an oral xylose load will be reflected in the time-dependent pattern of 13CO2 or 14CO2 exhaled in breath. Our objectives were to evaluate the diagnostic properties of 13C-xylose and 14C-xylose breath tests in coeliac disease, and to develop a diagnostic breath test index.

MATERIAL AND METHODS

We reviewed data from 41 coeliac patients who underwent the 14C-xylose breath test before and after commencement of a gluten-free diet, and 60 coeliac patients who underwent the 13C-xylose breath test, 37 of whom repeated the test after starting a gluten-free diet. Coeliac patients were compared with healthy control subjects.

RESULTS

Coeliac patients exhaled significantly less 13CO2 or 14CO2 than healthy controls during the first hour of the test and more isotope-labelled CO2 than control subjects after 3 h. Diagnostic accuracy was optimal with test duration of 210 min combining gas measurements at 30 min and 210 min in a simple fraction. This gas fraction index (30 min/210 min) distinguished between coeliac patients and healthy control subjects with 84-95% sensitivity and 87-94% specificity. After commencement of a gluten-free diet, the gas fraction index increased in most coeliac patients, but remained lower than that in healthy control subjects.

CONCLUSIONS

13C-xylose- and 14C-xylose breath tests discriminate between coeliac patients and healthy control subjects with high sensitivity and specificity. The stable isotope 13C-xylose breath test has comparable diagnostic accuracy to the radioactive isotope 14C-xylose breath test and should be the preferred alternative to traditional xylose absorption tests.

Sorbitol H2-breath test versus anti-endomysium antibodies to assess histological recovery after gluten-free diet in coeliac disease

BACKGROUND

Gluten-free diet plays a key role in treatment of coeliac disease, but it is difficult to evaluate its effect on improvement of villous architecture using sensitive non-invasive tests.

AIMS

To compare sorbitol H2-Breath Test with antiendomysial antibodies in the follow-up of coeliac disease to detect histological recovery

METHODS

A total of 38 consecutive patients with coeliac disease were studied. All underwent Sorbitol H2-Breath Test, antiendomysial and oesophagogastroduodenoscopy with multiple bioptic samples before diet and then 6, 12 and 18 months after gluten-free diet. Expiratory samples were collected before patients drank the test solution (5 g sorbitol in 150 ml tap water) and thereafter every 30 min for 4 hours. An increase in H2 concentration of > or = 20 ppm above fasting baseline was considered positive for sorbitol malabsorption. Antiendomysial antibodies were evaluated by the indirect immunofluorescent method.

RESULTS

Antiendomysial antibodies were positive in 32/38 patients before gluten-free diet (84.21%), while they were positive in 20/34 (54.82%), 2/16 (12.5%) and 0/2 (0%) cases after 6, 12 and 18 months of gluten-free diet, respectively, no correlation being found with improvement of histological lesions (p = ns). As far as concerns sorbitol H2-Breath Test, maximal cut-off value (in ppm) decreased progressively and parallel to histological recovery during follow-up. Indeed, it decreased from a mean 63 ppm before diet to 35, 19 and 12 ppm, after 6, 12 and 18 months of gluten-free diet, with a stetistical difference being found before and after (p < 0.001). Likewise, the peak value (in minutes) appeared progressively later during follow-up, parallel to histological recovery. In fact, it appeared at a mean of 119 minutes before gluten-free diet, while it appears at a mean of 164, 195 and 219 minutes after 6, 12 and 18 months on gluten-free diet. A statistical difference before and after start of gluten-free diet was found also in this case (p < 0.001).

CONCLUSIONS

Sorbitol H2-Breath Test is better than antiendomysial antibodies in revealing histological recovery in the follow-up of coeliac patients after the start of gluten-free diet due to its good correlation with histological damage. Moreover, it also appears to be able to detect dietary mistakes of the patients on gluten-free diet.

Using breath tests wisely in a gastroenterology practice: an evidence-based review of indications and pitfalls in interpretation

Breath tests are a simple and safe alternative to more invasive investigation strategies for many gastroenterological conditions. Both the hydrogen breath tests and the new 13C stable radioisotope breath tests are nonradioactive and safe in children and pregnancy. The range of diseases that can be identified include Helicobacter pylori infection, lactose and fructose intolerance, bacterial overgrowth, bile salt wastage, pancreatic insufficiency, liver dysfunction, and abnormal small bowel transit. In this review, the physiology supporting these tests and the principles of normal gas dynamics in the gut are briefly reviewed and then related to the test preparation and interpretation in two parts: 1) detection of H. pylori and 2) small bowel, pancreatic, and hepatobiliary disorders. A MEDLINE search reviewing all English language abstracts from 1966 to March, 2001 was performed, with an additional review of abstracts from major national meetings from 1997 to 2001. Using the information from this review, the performance characteristics of the various tests were detailed, and an attempt is made to provide some literature-based guidance regarding their indications and limitations. The interpretation of "flat" breath tests and the selective use of methane collection and colonic alkalinization are discussed. Breath tests are valuable tools that are, in general, underutilized in evaluating dyspepsia and functional bloating and diarrhea, as well as suspected malabsorption, including lactose intolerance.

Disappearance of endomysial antibodies in treated celiac disease does not indicate histological recovery

OBJECTIVE

Although serum IgA-class endomysial antibody (EmA) has high sensitivity for villous atrophy (VA) in patients with untreated celiac disease, few studies have attempted to correlate EmA seroconversion with histological recovery after starting a gluten-free diet. We prospectively studied changes in EmA status and in duodenal histology of seropositive patients after dietary treatment.

METHODS

Patients with VA and EmA had repeat EmA testing at 3, 6, and 12 months after starting gluten-free diet, plus assessment of dietary compliance by dietitians and follow-up duodenal biopsy at 12 months. VA before and after treatment was classified as partial (P), subtotal (ST), and total (T).

RESULTS

Of 77 patients with newly diagnosed VA and without IgA deficiency, 62 (81%) had EmA: 46 of 57 (81%) with T or STVA and 16 of 20 (80%) with PVA. Of 53 initially EmA-positive patients who completed study criteria, EmA was undetectable in 31 patients (58%) after 3 months' diet, in 40 (75%) after 6 months, and in 46 (87%) after 12 months. However, only 21 patients (40%), all seronegative by 12 months, had complete villous recovery. Only three (33%) of 10 patients with persisting ST or TVA and two (9%) of 22 with PVA remained EmA positive. Four of the five patients with persisting EmA had poor dietary compliance.

CONCLUSIONS

EmA is a poor predictor of persisting VA after patients have started gluten-free diet, although it may be of value in monitoring dietary compliance. Although there are no clear guidelines regarding the need for follow-up biopsy, EmA seroconversion cannot substitute. The apparent association between dietary compliance and seroconversion suggests that gluten intake may determine whether untreated celiac patients are EmA positive or negative for a given degree of small bowel damage.

D-xylose testing

The literature on D-xylose testing has been reviewed, stressing advances in our understanding of absorption in general (including D-xylose absorption), the relationship of D-xylose testing to the development of excellent serologic tests for the diagnosis of celiac disease, the use of D-xylose testing in the evaluation of diarrhea in acquired immunodeficiency syndrome, new information on breath testing for the evaluation of malabsorption, and recent information on the understanding of D-xylose absorption compared with transcellular vs. paracellular transport. The authors suggest ways in which D-xylose testing might be employed in malabsorption or diarrhea evaluations, including some algorithms.