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Query: UMLS:C0024523 (malabsorption)
 7,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Lactulose H2 breath tests are widely used for quantifying carbohydrate malabsorption, but the validity of the commonly used technique (interval sampling of H2 concentrations) has not been systematically investigated. In eight healthy adults we studied the reproducibility of the technique and the accuracy with which 5 g and 20 g doses of lactulose could be calculated from the H2 excretion after their ingestion by means of a 10 g lactulose standard. The influence of different lengths of the test period, different definitions of the baseline and the significance of standard meals and peak H2 concentrations was also studied. Regardless of baseline definition, estimates of malabsorption were most precise, if areas under the H2 concentration v time curves for four hours or more from the start of the excess H2 excretion were used. The median deviations from the expected values were 20-30% (5-60%, interquartile range). This corresponded to the deviation in reproducibility of the standard dose. We suggest that individual estimates of carbohydrate malabsorption by means of H2 breath tests should be interpreted with caution if tests of reproducibility are not incorporated. Both areas under curves and peak H2 concentrations seem valid for comparison of groups.
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PMID:Interval sampling of end-expiratory hydrogen (H2) concentrations to quantify carbohydrate malabsorption by means of lactulose standards. 231 30

Patients on chronic hemodialysis have decreased food intake and decreased fat stores. Malabsorption of carbohydrates such as lactose, sorbitol, or fructose cause functional bowel symptoms. The aim of this study was to assess the role of carbohydrate malabsorption in the nutritional abnormalities of chronic hemodialysis (CHD). Eleven patients on dialysis (six Hispanic, five black Americans) were studied, compared to 11 healthy volunteers age-, race-, and sex-matched. Lactulose 10 g (transit time), lactose 12.5 g, sorbitol 5 g, and fructose 37.5 g were tested fasting. Breath [H2] was measured 4 h postprandially by gas chromatograph analysis. Positive test was defined as 20 ppm [H2] above baseline. Weight, height, and triceps skinfold were measured. One hundred percent of CHD patients were below the 50th percentile for triceps skinfold measurement and 55% were below the 10th percentile. No biochemical abnormalities were noted. Breath [H2] tests: lactulose: all patients in both groups responded with positive tests. No difference in transit time was noted. Lactose: 73% of CHD had positive test compared to 36% control. Sorbitol: 73% of CHD had positive test compared to 27% control (p less than 0.05). Fructose: 27% CHD compared to 0% control. This study confirmed that CHD patients have decreased fat stores. It demonstrates for the first time that CHD patients have increased incidence of malabsorption of sorbitol. This carbohydrate malabsorption may contribute to the nutritional abnormalities of CHD.
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PMID:Carbohydrate malabsorption in black and Hispanic dialysis patients. 374 26

To quantify passage of unabsorbed dietary starch into the colon, 7 healthy volunteers had a multilumen tube positioned close to the ileocecal junction. Marker solution was perfused slowly, 20-40 cm above an aspiration site, to estimate, by marker dilution, flow through the ileum. On consecutive days, subjects ate liquidized meals containing 20 or 60 g starch; ileal aspirates were analyzed for starch and glucose for 5-6 h fasting and 4-7 h postprandially. Volume and carbohydrate concentrations were used to derive total carbohydrate traversing the ileum. In different subjects, unabsorbed carbohydrate was 453-4023 mg (2.3%-20.1%, mean 9.3%) for the smaller meal and 1332-6352 mg (2.2%-10.4%, mean 6.0%) for the larger. In 4 volunteers, hydrogen breath tests were performed on separate occasions after sucrose (50 g), lactulose (26 g), and the 20-g meal. Lactulose increased hydrogen excretion; sucrose and the test meal did not. We conclude that 2%-20% of dietary starch escapes absorption in the small bowel, confirming others' results using breath tests alone. Breath tests, though more convenient than intubation studies, may be a less sensitive index of starch malabsorption.
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PMID:Passage of carbohydrate into the colon. Direct measurements in humans. 687 5

In the rapidly increasing elderly population, diarrhoea as a result of drug therapy is an important consideration. The elderly consume a disproportionately large number of drugs for multiple acute and chronic diseases. Drugs can compromise both immune and nonimmune responses. Aging decreases the quality and proportion of T cells which in turn reduces the production of secretory IgA, the primary immune response of the gut. Acid production in the stomach decreases with increasing age and this compromise its vital 'self-sterilising' function, thus increasing the risk of diarrhoea due to viral, bacterial and protozoal pathogens. Other nonimmune defence mechanisms include the motility of the small intestine and the host-protective commensal bacteria of the colon. Drug induced hypomotility may result in bacterial overgrowth, deconjugation of bile salts and diarrhoea. Less commonly, diarrhoea may occur due to hypermotility because of a cholinergic-like syndrome. In the colon the host-protective commensal bacteria provide a powerful defence against pathogens. Disruption of this commensal population by antibiotic therapy may result in Clostridium difficile supra-infection which causes diarrhoea through toxin production. This is especially important in the elderly patient on chemotherapy for malignancy and those with multiple diseases. The organism responds to vancomycin, metronidazole and bacitracin. Metronidazole is the suggested drug of choice, with vancomycin reserved for relapses. Drugs also cause diarrhoea by interfering with normal physiological processes. Drugs impair fluid absorption by activating adenylate cyclase within the small intestinal enterocyte which increases the level of cyclic AMP. This causes active secretion of Cl- and HCO3-, passive efflux of Na+, K+ and water and inhibition of Na+ and Cl- into the enterocyte. Examples of these drugs (secretagogues) are bisacodyl, misoprostol and chenodeoxycholic acid (used to dissolve cholesterol gallstones). Drugs may also affect a second mechanism that regulates water and electrolyte transport, the Na+, K+ exchange pump. The energy for this pump is provided by the ATPase mediated breakdown of ATP. ATPase may be inhibited by digoxin, auranofin, colchicine and olsalazine. A number of drugs cause osmotic diarrhoea including antacids containing magnesium trisilicate or hydroxide. Lactulose is being used increasingly in compensated liver disease to increase protein tolerance and prevent hepatic encephalopathy. Sorbitol, an osmotic laxative agent also used in some liquid pharmaceutical preparations, induces diarrhoea by virtue of its osmotic potential. Another mechanism by which drugs cause diarrhoea is by mucosal damage of the small and large bowel. In the small intestine mucosal damage causes diarrhoea and fat malabsorption, as may occur with neomycin and colchicine. In the colon, for example, gold salts and penicillamine cause colitis of varying severity. Though the causes of diarrhoea are diverse, a drug-associated aetiology should always be considered and actively sought and addressed to prevent the complications of dehydration, electrolyte imbalance and undernutrition.
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PMID:Mechanisms of drug-induced diarrhoea in the elderly. 978 28

We sought to determine, in a piglet model, whether severe sugar malabsorption causes colonic injury or inflammation. Twenty-four piglets were randomized to receive either control formula (CON) or CON supplemented with lactulose (LAC) (N = 12 each group). After seven days, inflammation, apoptosis, and crypt cell proliferation were assessed in the proximal colon (cecum). Lactulose feeding caused persistent diarrhea. In both groups, breath H2 concentration was low, suggesting no increased fermentation in the LAC group. Weight gain/volume formula intake was identical in the CON and LAC groups (0.09+/-0.13 and 0.09+/-0.11 g/ml) respectively. Injury to the colon did not occur, but inflammation of the colon (scale 0-5) was greater in LAC (score of 1.5+/-1.38) than in CON (0.42+/-0.79; P<0.05). Cell proliferation at the basal 40% of the crypt was 92% increased in CON (labeling index 22.8+/-9.9 vs. 11.9+/-2.8; P<0.05). We conclude that persistent feeding during severe sugar malabsorption permits weight gain but may cause colitis.
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PMID:Lactulose feeding in piglets: a model for persistent diarrhea and colitis induced by severe sugar malabsorption. 1048 35

The excretion ratio of lactulose/mannitol in urine has been used to assess the extension of malabsorption and impairment of intestinal permeability. The recovery of lactulose and mannitol in urine was employed to evaluate intestinal permeability in children with and without diarrhea. Lactulose and mannitol probes were measured using high-performance liquid chromatography with pulsed amperometric detection (HPLC-PAD). Two groups of solutions containing 60 microM sugars were prepared. Group I consisted of glucosamine, mannitol, melibiose and lactulose, and group II of inositol, sorbitol, glucose and lactose. In the study of intra-experiment variation, a sample of 50 microl from each group was submitted to 4 successive determinations. The recovered amounts and retention times of each sugar showed a variation <2 and 1%, respectively. The estimated recovery was >97%. In the study of inter-experiment variation, we prepared 4 independent samples from groups I and II at the following concentrations: 1.0, 0.3, 0.1, 0.03 and 0.01 mM. The amounts of the sugars recovered varied by <10%, whereas the retention times showed an average variation <1%. The linear correlation coefficients were >99%. Retention (k'), selectivity (alpha) and efficiency (N) were used to assess the chromatographic conditions. All three parameters were in the normal range. Children with diarrhea presented a greater lactulose/mannitol ratio compared to children without diarrhea.
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PMID:Measurement of intestinal permeability using mannitol and lactulose in children with diarrheal diseases. 1058 31

Although often used as a reference standard in the breath hydrogen test (BHT), lactulose fermentation produces more hydrogen, compared to starch, and may therefore not be ideal. This study compares inulin with lactulose as reference standard in the study of carbohydrate malabsorption. Seventeen patients with malabsorption due to chronic pancreatitis and 15 normal controls were studied. Following overnight fasts, BHTs were performed after ingesting 10 g lactulose, 10 g inulin, and 200 g (16 g highly resistant starch) maize meal. Lactulose fermentation produced significantly more hydrogen than inulin in patients with malabsorption (97 +/- 20 vs 45 +/- 22 ppm x hr; P < 0.05) and controls (43 +/- 18 vs 21 +/- 10 ppm x hr; P < 0.05). Patients produced more hydrogen than controls with both standards (lactulose, 97 +/- 20 vs 43 +/- 18 ppm x hr, P < 0.05; inulin 45 +/- 22 vs 21 +/- 10 ppm x hrs; P < 0.05), suggesting adaptation of the colonic flora. Calculated CHO malabsorption was 2.5 +/- 0.8 vs 5.2 +/- 3.8 g with lactulose and 5.2 +/- 3.1 vs 11.2 +/- 9.6 g with inulin as standards in controls and patients, respectively (P < 0.05). Lactulose produces more breath hydrogen than inulin. Calculation of CHO malabsorption using these standards is therefore not comparable.
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PMID:Comparison of inulin and lactulose as reference standards in the breath hydrogen test assessment of carbohydrate malabsorption in patients with chronic pancreatic exocrine insufficiency. 1598 54

Lactose malabsorption is not always associated with intolerance symptoms. The factors responsible for symptom onset are not yet completely known. As differences in visceral sensitivity may play a role in the pathogenesis of functional symptoms, we evaluated whether an alteration of visceral sensitivity is present in subjects with lactose intolerance. Thirty subjects, recruited regardless of whether they were aware of their capacity to absorb lactose, underwent an evaluation of intestinal hydrogen production capacity by lactulose breath test, followed by an evaluation of lactose absorption by hydrogen breath test after lactose administration and subsequently an evaluation of recto-sigmoid sensitivity threshold during fasting and after lactulose administration, to ascertain whether fermentation modifies intestinal sensitivity. The role of differences in gastrointestinal transit was excluded by gastric emptying and mouth-to-caecum transit time by (13)C-octanoic and lactulose breath tests. Lactulose administration induced a significant reduction of discomfort threshold in subjects with lactose intolerance but not in malabsorbers without intolerance symptoms or in subjects with normal lactose absorption. Perception threshold showed no changes after lactulose administration. Severity of symptoms in intolerant subjects was significantly correlated with the reduction of discomfort thresholds. Visceral hypersensitivity should be considered in the induction of intolerance symptoms in subjects with lactose malabsorption.
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PMID:Visceral hypersensitivity and intolerance symptoms in lactose malabsorption. 1797 35

Hydrogen breath tests are widely used to explore pathophysiology of functional gastrointestinal (GI) disorders. Small intestinal bacterial overgrowth (SIBO) and carbohydrate malabsorption are disorders detected by these tests that have been proposed to be of great importance for symptoms of GI diseases. Glucose hydrogen breath test is more acceptable for diagnosis of SIBO whereas lactose and fructose hydrogen breath tests are used for detection of lactose and fructose maldigestion respectively. Lactulose hydrogen breath test is also used widely to measure the orocecal transit time for GI motility. These methods are noninvasive and inexpensive. Many patients with functional gut disorders are unaware of the relationship between diet and GI symptoms they present. In particular, patients with chronic symptoms may regard their condition as normal and may not be aware that their symptoms can be effectively managed following a proper diagnosis. Patients with symptoms of abdominal pain, bloating, flatulence and altered bowel movements (diarrhea and constipation), or with a medical diagnosis of irritable bowel syndrome or celiac disease, may have undiagnosed carbohydrate malabsorption or SIBO. Hydrogen breath tests are specific and sensitive diagnostic tests that can be used to either confirm or eliminate the possibility of carbohydrate malabsorption or SIBO in such patients. Breath tests, though valuable tools, are underutilized in evaluating dyspepsia and functional bloating and diarrhea as well as suspected malabsorption. However, because of their simplicity, reproducibility and safety of procedure they are now being substituted to more uncomfortable and expensive techniques that were traditionally used in gastroenterology.
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PMID:Hydrogen breath tests in gastrointestinal diseases. 2529 21