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Background: A severe neurological abnormality has not been previously described in individuals with hereditary fructose intolerance, which typically presents early in childhood with severe metabolic acidosis and hypoglycemia., Patient Description: We describe a boy who by age five years had required multiple admissions to the pediatric intensive care unit for an aggressive and atypical, relapsing and remitting neuropathy with features of acute motor axonal neuropathy (AMAN). It was later discovered that he also had undiagnosed hereditary fructose intolerance, and the severity and frequency of his neurological episodes diminished following an exclusion diet. His asymptomatic younger brother was diagnosed with hereditary fructose intolerance on screening. He is on a fructose-free diet and has not developed neurological symptoms., Conclusions: Ongoing low-level exposure to fructose prior to diagnosis may have contributed to our patient's neurological dysfunction. Early diagnosis and treatment may prevent neurological complications of hereditary fructose intolerance., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Malabsorption of carbohydrates such as fructose, lactose or sorbitol can often be detected among patients suffering from so-called non specific abdominal complaints. Sometimes the differential diagnosis may be difficult. So far successful treatment consists of dietary interventions only. Nevertheless, many questions are remaining still unanswered., (Copyright © 2011 Arab Journal of Gastroenterology. Published by Elsevier Ltd. All rights reserved.)

This review summarizes what is known about the effect of diet on irritable bowel syndrome (IBS) symptoms emphasizing data from randomized, controlled clinical trials. Studies suggest that IBS symptoms in one quarter of patients may be caused or exacerbated by one or more dietary components. Recent studies indicate that a diet restricted in fermentable, poorly absorbed carbohydrates, including fructose, fructans (present in wheat and onions), sorbitol, and other sugar alcohols is beneficial, but confirmatory studies are needed. Despite a long history of enthusiastic use, fiber is marginally beneficial. Insoluble fiber may worsen symptoms. Some patients with IBS, especially those with constipation, will improve with increased intake of soluble fiber. Prebiotic fibers have not been adequately tested. Daily use of peppermint oil is effective in relieving IBS symptoms. The usefulness of probiotics in the form of foods such as live-culture yogurt and buttermilk for IBS symptoms is not established. In clinical practice, it is very difficult to establish that a patient's symptoms result from an adverse reaction to food. A double blind placebo-controlled food challenge is the most reliable method, but it is not suitable for routine clinical use. A modified exclusion diet and stepwise reintroduction of foods or trials of eliminating classes of food may be useful.

The gastrointestinal tract possesses a huge epithelial surface area and performs many different tasks. Amongst them are the digestive and absorptive functions. Disorders of intestinal absorption and secretion comprise a variety of different diseases, e.g. coeliac disease, lactase deficiency or Whipple's disease. In principle, impaired small intestinal function can occur with or without morphological alterations of the intestinal mucosa. Therefore, in the work up of a malabsorptive syndrome an early small intestinal biopsy is encouraged in conjunction with breath tests and stool analysis to guide further management. In addition, there is an array of functional tests, the clinical availability of which becomes more and more limited. In any case, early diagnosis of the underlying pathophysiology is most important, in order to initiate proper therapy. In this chapter, diagnostic procedure of malabsorption is discussed with special attention to specific disease like coeliac disease, Whipple's disease, giardiasis and short bowel syndrome. Furthermore, bacterial overgrowth, carbohydrate malabsorption and specific nutrient malabsorption (e.g. for iron or vitamins) and protein-losing enteropathy are presented with obligatory and optional tests as used in the clinical setting.

Although incomplete fructose absorption has been implicated to cause gastrointestinal symptoms, foods containing high fructose corn syrup (HFCS) contain glucose. Glucose increases fructose absorption in healthy subjects. Our hypothesis was that fructose intolerance is less prevalent after HFCS consumption compared to fructose alone in healthy subjects and irritable bowel syndrome (IBS). Breath hydrogen levels and gastrointestinal symptoms were assessed after 40 g of fructose (12% solution) prepared either in water or as HFCS, administered in double-blind randomized order on 2 days in 20 healthy subjects and 30 patients with IBS. Gastrointestinal symptoms were recorded on 100-mm Visual Analogue Scales. Breath hydrogen excretion was more frequently abnormal (P < 0.01) after fructose (68%) than HFCS (26%) in controls and patients. Fructose intolerance (i.e. abnormal breath test and symptoms) was more prevalent after fructose than HFCS in healthy subjects (25% vs. 0%, P = 0.002) and patients (40% vs. 7%, P = 0.062). Scores for several symptoms (e.g. bloating r = 0.35) were correlated (P < or = 0.01) to peak breath hydrogen excretion after fructose but not HFCS; in the fructose group, this association did not differ between healthy subjects and patients. Symptoms were not significantly different after fructose compared to HFCS. Fructose intolerance is more prevalent with fructose alone than with HFCS in health and in IBS. The prevalence of fructose intolerance is not significantly different between health and IBS. Current methods for identifying fructose intolerance should be modified to more closely reproduce fructose ingestion in daily life.

We present the case of a 17-year-old male who was diagnosed at birth with hereditary fructose intolerance (HFI). The patient complained of morning-time asthenia and post-prandial drowsiness despite a correct sleep pattern. The physical examination and biological check-up only showed severe vitamin C deficiency (<10 mol/l; normal range: 26-84). The patient's tiredness was attributed to this vitamin C deficiency, which is a frequent side-affect of the fructose-free diet. A change in diet associated with a supplementation in vitamin C was advised, with an increase in vegetable intake, principally avoiding carrots, onions, leaks and tinned sweet-corn. This case offers the opportunity for a review of this rare disease. Two kinds of fructose metabolism disorders (both autosomal recessive) are recognized: 1) essential fructosuria caused by a deficiency of fructokinase, which has no clinical consequence and requires no dietary treatment; 2) HFI, linked to three main mutations identified in aldolase B gene that may be confirmed by fructose breath test, intravenous fructose tolerance test, and genetic testing. In HFI, fructose ingestion generally induces gastro-intestinal (nausea and vomiting, abdominal pain, meteorism) and hypoglycemic symptoms. Fasting is well tolerated. If the condition remains undiagnosed, it leads to liver disease with hepatomegaly, proximal tubular dysfunction, and slow growth and weight gain. In conclusion, endocrinologists should be aware of this rare metabolic disease in order to provide careful follow-up, particularly important when the patient reaches adulthood. Moreover, hypoglycemia induced by fructose absorption, unexplained liver disease, irritable bowel syndrome or familial gout in an adult is suggestive of the diagnosis.

Background: Fructose malabsorption is characterized by the inability to absorb fructose efficiently. As a consequence fructose reaches the colon where it is broken down by bacteria to short fatty acids, CO2 and H2. Bloating, cramps, osmotic diarrhea and other symptoms of irritable bowel syndrome are the consequences and can be seen in about 50% of fructose malabsorbers. We have previously shown that fructose malabsorption is associated with early signs of mental depression and low serum tryptophan concentrations. It was therefore of interest whether a fructose-reduced diet could not only improve gastrointestinal complaints but also depressive signs seen in fructose malabsorbers., Methods: Fifty-three adults (12 males, 41 females), who were identified as fructose malabsorbers according to their breath-H2 concentrations, filled out a Beck's depression inventory-questionnaire, and a questionnaire with arbitrary scales for measurement of meteorism, stool frequency and quality of life for a 4-week period before dietary intervention and 4 weeks after dietary change as for fructose- and sorbitol-reduced diet., Results: Depression scores were reduced by 65.2% after 4 weeks of diet (P < 0.0001), and there was a significant reduction of meteorism (P < 0.0001) and stool frequency (P < 0.01). Improvement of signs of depression and of meteorism was more pronounced in females than in males., Conclusion: Fructose- and sorbitol-reduced diet in subjects with fructose malabsorption does not only reduce gastrointestinal symptoms but also improves mood and early signs of depression.

A patient is described who presented with the signs and symptoms of hereditary fructose intolerance a few hours after her first fructose challenge. The diagnosis was confirmed by the demonstration of reduced activity of hepatic aldolase B towards fructose-1-phosphate. A second liver biopsy 10 months later had normal aldolase B activity towards fructose-1-phosphate and a fructose tolerance test was also normal. A possible explanation for these findings is proposed.

Examination of glucose kinetics, pancreatic alpha and beta cell function, plasma lipids, urinary acidification and calcium excretion has been undertaken in a patient with hereditary fructose intolerance. This case was unusual as it was associated with insulin-requiring diabetes, type IV hyperlipemia, hypercalciuria and renal calculi. He also demonstrated the previously described fructose-induced defect of urine acidification. Glucagon and C-peptide assays showed that the pancreatic alpha cells were stimulated by fructose and that the beta cells did not respond to fructose. It is not known whether the latter was due to his diabetes or to the lack of a beta cell response to this sugar. Primed 14C-glucose infusions were used for the first time to study nonsteady state glucose kinetics in man. They showed that, 24 hours after the last insulin injection and under basal conditions, the glucose concentrations increased because glucose production exceeded glucose utilization. However, after the administration of sorbitol the plasma glucose concentration decreased because glucose production decreased. After the administration of sorbitol there was no change in the metabolic clearance of glucose. This reflects the lack of a peripheral insulin effect and is consistent with the lack of any measurable C-peptide. Glucose utilization also decreased, but this decrease was less than the decrease in glucose production. Because the metabolic clearance of glucose remained unchanged, it was concluded that the change in glucose utilization was solely due to the decrease in glucose concentration. The absence of C-peptide in the plasma indicated that changes in glucose turnover were not related to any changes in endogenous plasma insulin. Furthermore, the plasma glucagon concentration increased and, hence, changes in this hormone could not account for the decrease in glucose production. Therefore, it was concluded that the sorbitol-induced decline in glucose production was due to a direct effect on hepatic metabolism.

Persons with HFI follow a lifelong, self-imposed, sucrose-restricted diet in which foods containing sucrose are consumed infrequently. Our subjects with HFI had a total sucrose intake that was approximately 5% that of control subjects and had a caries score (DMFS) that was less than 10% that of control subjects. No significant differences were found in the oral hygiene status (plaque or oral hygiene indexes) of the two groups. Foods containing starch, in the absence of sucrose, are not articularly inducive to caries. The daily intake of sucrose of the control group was less than expected. Consumption of sucrose is, therefore, less than estimates calculated by per capita sucrose disappearance. We consider that caries is initiated when the sucrose content of the diet and the frequency of ingestion exceed a low limit.

An 18-yr-old man with a classical history of hereditary fructose intolerance (HFI) developed typical biochemical changes following an oral fructose load: fructosemia, hypoglycemia, hypophosphatemia, hyperuricemia, and metabolic acidosis. Hypokalemia (3.1 meq/liter) was also noted. Three aspects of this case expand the published literature on this syndrome: (1) Metabolic acidosis was found to be due to both lactic acidosis and proximal renal tubular acidosis (RTA). We could quantitate the relative contribution of each, and found that urinary bicarbonate loss due to proximal RTA accounted for less than 10% of the fall in serum bicarbonate. The major cause of the metabolic acidosis was lactic acidosis. (2) Hypokalemia was found to be due to movement of potassium out of the extracellular space rather than to urinary loss. Potassium may have entered cells with phosphate or may have been sequestered in the gastrointestinal tract. (3) The coexistence of proximal RTA and acidemia made it possible to study the effect of acidemia on the urine-blood partial pressure of carbon dioxide (PCO2) gradient in alkaline urine (U-B PCO2). The U-B PCO2 measured during acidemia was much higher at the same urine bicarbonate concentration than in normal controls during alkalemia, providing evidence in humans that acidemia stimulates distal nephron hydrogen-ion secretion.

Abnormalities of renal handling of urate occur in a wide variety of physiological and pathological conditions and are mediated by factors including renal blood flow, glomerular filtration rate, urine flow rate, urinary constituents, metabolites, hormones and drugs. The determination of the aetiological factors in each abnormal situation is complex and the problem is discussed in relation to a variety of conditions including renal tubular disorders and mental intoxications, hypertension, toxaemia of pregnancy, glycogen storage disease, fructose administration, hereditary fructose intolerance, as well as obesity, regular alcohol consumption and hyperlipoproteinaemia. Apart from those diseases, usually genetically determined, which are associated with excessive production of urate, the most common causes of hyperuricaemia act at a renal level and result in a reduction in the net renal excretion of urate.

In 84 children suffering from chronic insufficiency of digestion, ossification of both hands was observed by means of fluoroscopic controls for several years. In 48 of 71 patients there was a retarded ossification; in 23 it was normal, or respectively more advanced. 18 boys and girls succeeded in making up for there retardation by means of consequent diet so that it might be regarded as a "spurt of growth". But in 10 of them retardation was constant, and in 14 children it increased. The causes of insufficient improvement were: late diagnosis and therapy, failures of diet, but also additional diseases--different from digestive insufficiency--, and long-term use of corticosteroides. In 30 of 84 children ossification was always normal or advanced. They had received early and consequent diet for years. Only in few cases, slight or moderate diseases were diagnosed. Development of ossification was parallel to body height, but not to weight gain.