Confirming persistence of gluten intolerance in children diagnosed as having coeliac disease in infancy

The clinical response to gluten challenge: a review of the literature

The aim of this review was to identify, evaluate and summarize all relevant studies reporting on the clinical response to gluten challenge by adult or pediatric patients with suspected or diagnosed coeliac disease (CD) on a gluten-free diet. We evaluated the effect of gluten challenge on changes in symptoms, intestinal mucosa histology, and serum antibodies. A systematic electronic search was performed for studies published as of 1966 using PubMed and Scopus databases. In the reviewed studies, doses ranged from 0.2 to 30 g/day of wheat gluten or comprised a gluten-containing diet. The onset of symptoms upon gluten intake varied largely from days to months and did not parallel serum antibody or histological changes. Within 3 months of gluten challenge, 70%-100% of pediatric CD patients became positive for AGA-IgA and EMA-IgA antibodies and 50%-70% for AGA-IgG. A limited number of trials suggest that no more than half of adult patients developed positive AGA-IgA, EMA-IgA, tTG-IgA or DGP-IgA/IgG titers. Approximately 50%-100% of pediatric and adult patients experienced mucosal relapse of gluten provocation within 3 months, which was preceded by increased mucosal intra-epithelial lymphocytes within several days of challenge. A 3-month high-dose gluten challenge should be suitable to diagnose the majority of CD patients. In some cases prolonged challenge may be needed to verify diagnosis. Combination testing for antibodies and mucosal histology may fasten the diagnosis.

D-xylose testing: a review

The efficacy of D-xylose testing in clinical situations has been reviewed in the light of recent kinetic studies. The standard 25-g D-xylose test in adults, based on analysis of 5-h urine collection and a 1-h serum sample, discriminates between normal subjects and patients with proximal small intestinal malabsorption with greater than 95% specificity and sensitivity. The 1-h serum level measured after administering this dose is also useful in evaluating malabsorption in patients with intermediate degrees of renal insufficiency and in the elderly. The 1-h serum test after administration of 5 g of D-xylose should be used in pediatrics and is greater than 91% sensitive and close to 100% specific. The [14C]D-xylose breath test with 1 g of D-xylose has been useful in identifying malabsorption caused by bacterial overgrowth in the small intestine.

Gastrointestinal hypersensitivity to cow's milk protein: the diagnostic value of gut function tests

Thirty-six children with suspected gastrointestinal hypersensitivity to cow's milk protein were investigated before and after challenge with cow's milk protein by one or more of four tests of gut function: the appearance of small bowel mucosa, mucosal disaccharidase levels, a 1-h blood-xylose test, and a 50 g-lactose breath-hydrogen test. These tests were not always abnormal in children who had definite adverse reactions to milk. Conversely changes were seen in some with negative milk challenges. Although small bowel biopsy, assessment of disaccharidase activity and perhaps the breath-hydrogen test have an important place in the pre-challenge assessment to exclude other causes of gastrointestinal symptoms, these gut function tests and the 1-h xylose test done following milk provocation do not appear to have any advantage over careful clinical observation.

Changes in N-terminal glucagon-like immunoreactivity and insulin during short-term gluten challenge in childhood coeliac disease

Sixteen patients (aged 3.5-14.3 years) with normal jejunal mucosa, originally diagnosed as having coeliac disease at least 18 months before, were started on gluten challenge. The 'end point' of challenge was significant deterioration in jejunal mucosa morphologically and morphometrically. Studies carried out both before and after challenge included intestinal absorption of D-xylose and glucose, and release of insulin and N-terminal glucagon-like immunoreactivity (N-GLI). After gluten challenge, there were significant increases in plasma N-GLI at both 45 (P less than 0.05) and 120 minutes (P less than 0.03) after oral glucose. Significant reduction occurred in glucose absorption at 45 minutes (P less than 0.04), in one-hour D-xylose absorption (P less than 0.01) and fasting serum cholesterol (P less than 0.01). Plasma N-GLI showed significant negative correlations with D-xylose absorption (P less than 0.003) and serum cholesterol (P less than 0.004).

Neonatal gut function, measured by the one hour blood D (+) xylose test: influence of gestational age and size

D(+) Xylose absorption, assessed by one hour blood xylose levels, has been measured after intraduodenal infusion of the sugar in 35 infants of differing gestational age and size. The test was performed between the 2nd and 6th days of life. Full-term appropriately grown infants had higher blood xylose levels (1.41+/-0.07 mmol/l) at one hour than pre-term appropriately grown infants (1.17+/-0.07 mmol/l; P less than 0.05), or 'light for dates' infants, both full-term (0.73+/-0.06 mmol/l; P less than 0.001) and pre-term (0.96+/-0.17 mmol/l; P less than 0.05). Serial studies of 11 infants were made two to five times between the 3rd and 20th day of life. The levels for one hour xylose rose in all groups, but the 'light for dates' infants showed the least rise. There was no sign of catch-up in this group, and some results appeared to fall further behind those of appropriately grown infants. These results suggest that the primal small intestine is maturing in the perinatal period, and that intrauterine growth retardation may impair intestinal absorption. The nutritional significance is not known.

Reintroduction of gluten in adults and children with treated coeliac disease

Twenty-eight patients, thought to have coeliac disease and on gluten free diets, were put on a normal diet to confirm their diagnoses. Nineteen had been diagnosed in adult life (ACD) and nine in childhood (CCD). Patients were assessed on jejunal, morphological, and symptomatic parameters. Eighteen patients with ACD relapsed within seven weeks. Nine patients with CCD relapsed at variable times but five took longer than seven weeks, the longest period beint 10 months. Seven patients had no symptoms despite morphological deterioration during challenge and one patient, with ACD, did not relapse and was HLA B8 negative. This patient with ACD had subtotal villous atrophy on two jejunal biopsies and later showed morphological improvement on a gluten free diet. There was no correlation between the relapse time and time spent on a gluten free diet.

One-hour blood-xylose test in diagnosis of cow's milk protein intolerance

In this prospective study, 18 consecutive children suspected of cow's milk protein intolerance (C.M.P.I.) on clinical grounds were investigated before and after challenge with cow's milk. One-hour blood-xylose, serum-IgE, eosinophil count, serum-complement (C3) and a jejunal biopsy specimen for histology and disaccharidase activity were obtained from all patients before challenge. Serum-complement was measured again 24 h after the beginning of the challenge and the first three tests were repeated on the fifth day. A second jejunal biopsy was obtained in 9 of the first 10 children. 15 of the 18 children were considered to have C.M.P.I. The one-hour blood-xylose test emerged as a simple and valuable test in the diagnosis of C.M.P.I. A significant drop (51--81%) in the one-hour blood-xylose level was observed in all 15 patients. In all patients but one it dropped below 25 mg/dl. Mean value (+/- S.D.) for the group was 47.5 +/- 11.1 mg/dl before and 17.2 +/- 4.2 mg/dl after cow's milk ingestion.

Variability of gluten intolerance in treated childhood coeliac disease

Fifty children consecutively attending a clinic for coeliac disease co-operated in a trial; 10 found to have flat mucosa were excluded. Forty children of mean age 9.8 years, whose duodenal or jejunal mucosa had returned to normal or near normal appearance after a mean of 5.8 years on gluten-free diets, were put back on normal diets. In 37, mucosal occurred in a mean of 16.9 months (four to 74 months). Four of the 37 had serial biopsies, in which mucosal enzymes (particularly lactase) fell and interepithelial lymphocyte counts rose before the mucosal morphology was regarded as definitely 'coeliac'. Three children had normal mucosal appearance after 58 to 73 months on normal diets, one of whom showed temporary mucosal abnormalities, another having occasionally low enzymes, in both suggesting underlying gluten sensitivity. Lactase suppression and raised IEL counts appear to be sensitive indicators of gluten intolerance. In our experience, a diagnosis of coeliac disease based on severe mucosal damage and a satisfactory response to a gluten-free but milk-containing diet implies a very strong likelihood of permanent or prolonged gluten intolerance, but with a striking variability in its expression.

The influence of gestational age and size on the absorption of D-xylose and D-glucose from the small intestine of the human neonate

D-Xylose absorption (using the one-hour blood levels) and active D-glucose absorption (calculated from changes in transmural electrical potential difference) have been measured after intraduodenal infusion of the appropriate sugar, in groups of neonates who were full-term or preterm, and who were in addition either appropriately sized for gestational age, or growth-retarded in utero. The one-hour D-xylose blood levels were significantly lower in preterm infants, and were even lower in the growth-retarded group. In follow-up studies D-xylose absorption rose in all groups of infants over the first three weeks of postnatal life but there was no sign of 'catch-up' in the results of the growth-retarded infants. In the studies of D-glucose absorption the theoretical kinetic parameters 'apparent P.D.max' (equivalent to Vmax) and 'apparent Km' were calculated. Normal full-term infants had values for both parameters that were approximately two-thirds of published adult values. Malnourished neonates had significantly lower P.D.max and apparent Km, and preterm infants had a lower P.D.max, than the values obtained in those infants who were full-term and appropriately grown.

Gluten challenge in treated coeliac disease

Thirty-two children with a past diagnosis of coeliac disease were reinvestigated by means of gluten challenge. They had received a gluten-free diet for a mean period of 6-5 years (range 0-25-11-0) before gluten challenge, and had a mean age of 9-9 years (range 3-0-15-3) at the onset of challenge. Small intestinal biopsies were performed before and after the gluten challenge (at least 10 g natural gluten per day for 3 months in the majority) and, as judged by light microscopy and morphometric techniques, coeliac disease was confirmed in 25 (78%) of the 32 patients; challenge was continued in the remaining 7 for a total period of 2 years when biopsies were repeated in 6 children and all were normal. Serum and RBC folate, serum iron, Hb level, and clinical symptoms were unpredictable variables in identifying children who developed gluten-induced enteropathies. The social and emotional effects of gluten challenge are discussed. The results highlight the importance of gluten challenge and intestinal biopsy in the diagnosis of coeliac disease and strongly suggest that a normal biopsy after a 3-month gluten challenge (as described above) excludes coeliac disease.

Value of 1-hour blood-xylose test in diagnosis of childhood coeliac disease

In a series of 46 children with untreated coeliac disease and in 102 controls with normal mucosa the 1-hour blood-xylose test was, in view of its simplicity, of much value in the diagnosis of childhood coeliac disease. Only one blood-xylose result was falsely normal in the 46 coeliac patients. It is concluded that a normal blood-xylose value does not exclude coeliac disease and should not prevent peroral biopsy in the presence of strong clinical suspicion. On the other hand, patients who have repeatedly abnormal blood-xylose values merit an intestinal biopsy even in the absence of suggestive clinical symptoms.

One-hour blood xylose test: a reliable index of small bowel function

A retrospective analysis of oral D-xylose tolerance tests in 435 pediatric patients was performed. A significant difference was found between 126 normal subjects and 47 untreated children with celiac disease one hour after load. The one-hour value was found to be more reliable than was fecal fat analysis in screening children for celiac disease. Sex, age, weight, and body surface did not influence the results of the one-hour value in the control subjects. Forty-eight children with cystic fibrosis had one-hour xylose levels within the normal range, but the means at 90, 120, and 180 minutes after load exceeded significantly (P less than 0.01) those of the controls. In a nonceliac group of 63 children with abnormally low xylose levels, almost all were found to have clinical conditions compatible with upper small bowel mucosal impairment. This study shows that a single estimation of xylose in blood one hour after load is a reliable index of small bowel mucosal function. It is a good screening test for celiac disease and small bowel disorders producing malabsorption in children.

Coeliac disease in Sudanese children

Coeliac disease has not hitherto been documented in Sudanese children. This report describes seven Sudanese children with coeliac disease of whom two are siblings. They all had evidence of impaired intestinal absorption, severe histological changes of their jejunal mucosa with clinical and histological improvement on gluten free/sorgham free diet. Subsequently one patient had a clinical relapse when gluten was reintroduced; four had positive gluten challenge using serial one hour blood xylose estimation. They all belonged to the upper socioeconomic group of the society in the north of the Sudan.

The 15 g D-xylose absorption test: its application to the study of coeliac disease

The absorption of xylose following an oral load of 15 g D-xylose has been studied by serial blood levels in 17 untreated adult coeliac patients, 21 treated coeliac patients, and 30 non-coeliac patients. A statistically significant difference in xylose blood levels was found between untreated coeliac and non-coeliac patients at all the times studied, but a complete separation between these two groups occurred only at the 75 minute stage. The reproducibility of absorption was assessed by repeating the test in 16 subjects. The 95% confidence limits of the standard error of estimate are narrowest at 75 and 90 minutes.

Standardised approach to gluten challenge in diagnosing childhood coeliac disease

Thirty-five children, in whom coeliac disease had been diagnosed on inadequate grounds and who had been on a gluten-free diet for one to 10 years, were challenged with gluten in accordance with a standardised procedure. All children were admitted to hospital for 48 hours for general assessment, two one-hour blood xylose tests, and the introduction of gluten. Thirty children underwent a pre-challenge peroral jejunal mucosal biopsy; the specimens were either normal or showed slight non-specific abnormalities. Gluten powder 20 g/day was given in addition to an otherwise gluten-free diet. The children were reassessed as outpatients every two weeks, when a one-hour blood xylose test was performed. Repeat biopsy was performed when xylose absorption fell or after three months. Seventeen children had abnormal post-challenge biopsy appearances compatible with coeliac disease in relapse; 14 of these children completed their challenge within eight weeks. Seventeen children had completely normal biopsy appearances at the end of three months and were returned to a normal diet. One to two years later eight underwent repeat biopsies, which showed nothing abnormal. In only one child, the oldest in the series, were the histological findings equivocal. In the 17 children in whom coeliac disease was confirmed the duration of gluten challenge was not related to age, duration of gluten-free diet, histological findings on the pre-challenge biopsy, or HLA status.

Criteria for diagnosis of temporary gluten intolerance

Strict criteria for the diagnosis of temporary gluten intolerance are formulated in the light of the case of an 8-week-old infant with severe diarrhoea and failure to thrive, who recovered on an elimination diet that was gluten-free. 8 weeks later an oral challenge with 2.5 g twice daily of powdered gluten for one day produced diarrhoea, weight loss, and impaired xylose absorption. Gluten was successfully reintroduced into the diet 9 months later without incident. Jejunal histology remains normal after 26 months of a daily diet that contains 5 to 10 g gluten.