Diagnostic Utility of Carbohydrate Breath Tests for SIBO, Fructose, and Lactose Intolerance.

BACKGROUND: Unexplained bloating, gas, and pain are common symptoms. If routine tests are negative, such patients are often labeled as irritable bowel syndrome. AIMS: To determine the diagnostic utility of breath tests that assess for small intestinal bacterial overgrowth (SIBO), fructose or lactose intolerance, and the predictive value of symptoms. METHODS: Patients with gas, bloating, diarrhea, abdominal pain (≥ 6 months), and negative endoscopy and radiology tests were assessed with symptom questionnaires, glucose (75 g), fructose (25 g), or lactose (25 g) breath tests. Breath tests were categorized as positive when H2 (≥ 20 ppm) or CH4 (≥ 15 ppm) increased above baseline values or as hypersensitive when symptoms changed significantly without rise in H2/CH4 or as negative. RESULTS: 1230 patients (females = 878) underwent 2236 breath tests. The prevalence of SIBO was 33% (294/883), fructose intolerance was 34% (262/763), and lactose intolerance was 44% (260/590). Hypersensitivity was found in 16% and 9%, respectively, during fructose and lactose breath tests. Although gas (89%), abdominal pain (82%), and bloating (82%) were highly prevalent, pretest symptoms or their severity did not predict an abnormal breath test, but symptoms during the breath test facilitated diagnosis of SIBO, fructose, and lactose intolerance and hypersensitivity. CONCLUSIONS: Approximately 45% of patients with unexplained gas and bloating had SIBO, fructose, or lactose intolerance; another 9-16% had visceral hypersensitivity. Pretest symptoms were poor predictors, but symptoms during the breath tests were useful. Breath tests are safe, provide significant diagnostic yield, and could be useful in routine gastroenterology practice.

Roles of Lactose and Fructose Malabsorption and Dietary Outcomes in Children Presenting with Chronic Abdominal Pain.

Intolerance to lactose or fructose is frequently diagnosed in children with chronic abdominal pain (CAP). However, the causal relationship remains a matter of discussion. A cohort of 253 patients, aged 7-12 years, presenting with unexplained CAP received standardized diagnostics. Additional diagnostic tests were performed based on their medical history and physical and laboratory investigations. Fructose and lactose hydrogen breath tests (H2BT) as well as empiric diagnostic elimination diets were performed in 135 patients reporting abdominal pain related to the consumption of lactose or fructose to evaluate carbohydrate intolerance as a potential cause of CAP. Carbohydrate malabsorption by H2BT was found in 55 (41%) out of 135 patients. An abnormal increase in H2BT was revealed in 30% (35/118) of patients after fructose consumption and in 18% (20/114) of patients after lactose administration. Forty-six percent (25/54) reported pain relief during a diagnostic elimination diet. In total, 17 patients had lactose malabsorption, 29 fructose malabsorption, and nine combined carbohydrate malabsorption. Carbohydrate intolerance as a cause of CAP was diagnosed at follow-up in only 18% (10/55) of patients with malabsorption after the elimination of the respective carbohydrate. Thus, carbohydrate malabsorption appears to be an incidental finding in children with functional abdominal pain disorders, rather than its cause. Therefore, testing of carbohydrate intolerance should only be considered in children with a strong clinical suspicion and with the goal to prevent long-term unnecessary dietary restrictions in children suffering from CAP.

Lactante con vómitos, hipertransaminasemia y fiebre: un diagnóstico insospechado / Infant with vomiting, elevated transaminases and fever: An unsuspected diagnosis

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Inborn errors of carbohydrate metabolism.

Glycogen storage diseases (GSD) and inborn errors of galactose and fructose metabolism are the most common representatives of inborn errors of carbohydrate metabolism. In this review the focus is set on the current knowledge about clinical symptoms, diagnosis and treatment. Hepatomegaly and hypoglycaemia are the main findings in liver-affecting GSD like type I, III and IX. Diagnosis is usually made by non invasive investigations, e.g. mutation analysis. In GSD I, a carbohydrate balanced diet with frequent meals and nocturnal continuous tube feeding or addition of uncooked corn starch are the mainstays of treatment to prevent hypoglycaemia. Liver transplantation has been performed in different types of GSD. It should only be considered in high risk patients e.g. with substantial cirrhosis. Many countries have included classical galactosaemia in their newborn screening programs. A lactose-free infant formula can be life-saving in affected neonates whereas a strict fructose-restricted diet is indicated in hereditary fructose intolerance.

Plasma lysosomal enzyme activities in congenital disorders of glycosylation, galactosemia and fructosemia.

BACKGROUND: Variable increases in the plasma activity of different lysosomal enzymes have been reported in patients with congenital disorders of glycosylation (CDG). In particular, elevated plasma aspartylglucosaminidase activity (AGA) has been found in the majority of CDG type I patients. We report on the plasma activity of AGA and other lysosomal enzymes in patients with different types of primary and secondary CDG defects. METHODS: AGA, alpha-mannosidase, beta-mannosidase and beta-hexosaminidase activities were assayed in the plasma of patients with CDGI (4CDGIa, 4CDGIx) and CDGIIx (5, all with a combined N- and O-glycosylation defect), classical galactosemia (GALT) (n=3) and hereditary fructose intolerance (HFI) (n=2). RESULTS: Increased AGA and beta-hexosaminidase activities were found in all and 7/8 of the GDGI patients respectively. All enzymic activities were normal in the CDGIIx patients. Elevated AGA and beta-hexosaminidase activity was also seen in GALT and HFI patients before treatment, when transferrin isoelectric focusing (TfIEF) patterns were also abnormal. CONCLUSIONS: Increased AGA plasma activity, although a consistent finding in CDGI patients, is not specific to this group of disorders since it is also observed in untreated cases of GALT and HFI. Furthermore, plasma AGA activity cannot serve as a marker for CDGII disorders. In conjunction with TfIEF it could be used in the follow up of GALT and HFI patients.

Hereditary fructose intolerance and celiac disease: a novel genetic association.

BACKGROUND & AIMS: Celiac disease (CD) has been associated with several genetic disorders, but has not been associated with hereditary fructose intolerance (HFI). METHODS: We identified CD in 4 female patients affected by HFI from among 38 Italian HFI patients. RESULTS: Three of these patients were children in whom the CD-associated signs were hypertransaminasemia, failure to thrive, low weight, and short stature, whereas the adult patient had protracted diarrhea notwithstanding a fructose-free diet. The incidence of CD in our group of HFI patients was higher (>10%) than in the general population (1%-3%) (P<.02). CONCLUSIONS: The possibility of an association between these 2 gastrointestinal disorders is important, particularly in the management of HFI patients with persisting symptoms.

Colonic bacterial activity determines the symptoms in people with fructose-malabsorption.

BACKGROUND/AIM: This study was performed to find a parameter to discriminate symptomatic from asymptomatic subjects with fructose-malabsorption. PATIENTS AND METHODS: Thirty-four subjects (12 m, 22 f; average age, 28.6 years; range 16-60) were investigated after an overnight fast. After intake of 25 g fructose, H2-tests were carried out. Endexspiratory breath samples were taken before the ingestion of the tested sugar and at 30 minute intervals over a 2 hour period. Hydrogen determination was performed immediately after sampling. Results were considered pathological if there was a rise in hydrogen over 20 ppm and a twofold increase from the initial value. Aerobic and anaerobic cultures from stool bacteria were set and incubated with 0.5 g fructose. RESULTS: Among 34 healthy controls, 13 malabsorbers (38%) were detected. Out of these malabsorbers, 6 (46%) reported gastrointestinal concomitant symptoms. Symptomatic and asymptomatic subjects with fructose-malabsorption showed a comparable increase in hydrogen levels. The disappearance rate of fructose in the stool cultures was significantly elevated in the symptomatic group compared with the asymptomatic, but only in the anaerobic culture. CONCLUSION: This activity of colonic bacteria, significantly discriminating symptomatic subjects with fructose-malabsorption from asymptomatic, enhances the importance of fructose-malabsorption in the differential diagnosis of people with non-specific abdominal complaints. Antibiotic therapy in severe cases should be considered a therapeutical approach. Moreover these results may support the role of nutritional carbohydrates in the pathogenesis of colonic diseases.

Biochemical and clinical observations in four patients with fructose-1,6-diphosphatase deficiency.

Three boys and one girl suffering from inherited fructose-1,6-diphosphatase (FDPase) deficiency are reported. All four patients had less than 25% residual hepatic FDPase activity. While in two out of three patients the enzyme deficiency was also expressed in leucocytes, one patient had a normal enzyme activity. Remarkably, three patients had pronounced neonatal hyperbilirubinaemia requiring exchange transfusion.

[Adults with hereditary fructose intolerance: risks of fructose infusion]. / Erwachsene mit hereditärer Fructoseintoleranz: Gefährdung durch Fructoseinfusion.

After her first grand mal seizure a 30-year-old woman was given a fructose infusion by an emergency doctor. On admission to hospital she complained of severe nausea. Ultrasonography revealed hepatosplenomegaly and the gamma-GT concentration was raised to 25 U/l. As hyperinsulinism was suspected an oral glucose tolerance test was suggested, but refused by the patient. She reported marked aversion to all sweet foods. Examination of an endoscopically obtained liver biopsy revealed clear reduction in fructoaldolase activity in liver tissue, i.e. the diagnosis of hereditary fructose intolerance. Three of the patient's siblings were also affected. The widespread use of infusion solutions containing sorbitol and fructose has twice proved acutely hazardous in this patient and is generally life-threatening for persons with an inborn error of metabolism whose pathologic status often remains undiagnosed to an adult age.

Isolated fructose malabsorption.

A patient with isolated fructose malabsorption presented with diarrhoea and colic during the first year of life and subsequently responded to a fructose free diet. Fructose malabsorption has been implicated in some cases of irritable bowel syndrome in adults and may also be an infrequently recognised cause of gastrointestinal symptoms in children.

[Congenital fructose 1,6 diphosphatase deficiency. Description of a case]. / Deficit congenito di fruttosio 1,6 difosfatasi. Descrizione di un caso.

In describing one case of congenital fructose 1,6-diphosphatase deficiency the Authors review the several clinical conditions giving problems of differential diagnosis. For certain diagnosis they underline the importance of liver biopsy, to dose the deficient enzyme directly in the liver tissue.

[Hereditary intolerance to fructose in infants. Presentation of a clinical case]. / L'intolleranza ereditaria al fruttosio del lattante. Presentazione di un caso clinico.

One case of hereditary fructose intolerance is examined: the disease was known exceptionally early when the baby was about two months old. The case is classified and described with the metabolic alterations typical of the syndrome and then it is examined stressing the difficulty in diagnosing it at such an early stage of the baby's life and the possibility of worsening the symptoms with unsuitable treatments (i.e. use of solutions fructose-containing). The author concludes advising to use the utmost care in feeding the baby since its birth in order to avoid an early administration of potentially dangerous carbohydrates.