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

The 14C-triolein breath test was evaluated as a screening test for fat malabsorption in 50 consecutive patients. After the ingestion of a 30-g fat meal containing 5 microCi 14C-triolein, the breath excretion of 14CO2 was measured at hourly intervals for 6 h and compared with a 3-day faecal excretion of fat. Nineteen patients had steatorrhoea and 31 patients normal fat excretion. The maximum specific activity of CO2 in the breath provided the best means of distinguishing between the two groups, with no false-negative values and nine false-positive values (29%). Our findings confirm that the 14C-triolein breath test is sensitive and has sufficient specificity for screening fat malabsorption, especially among outpatients. If a normal 14C-triolein breath test is obtained, it seems unnecessary to perform measurements of excretion of faecal fat.
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PMID:14C-triolein breath test as a rapid and convenient screening test for fat malabsorption. 667 78

Short-chain fatty acids (SCFAs) constitute the major solute fraction of normal stool water and are responsible for the diarrhea associated with carbohydrate (CHO) malabsorption. Although SCFA absorption from the human small bowel has been reported previously, the fate of SCFAs in the colon--their major site of production--was investigated in the present study. The colon of normal volunteers was perfused with neutral, isotonic solutions containing SCFA, 0-90 mM. Propionate was studied in detail with limited observations on acetate and n-butyrate. SCFA absorption was concentration-dependent; back diffusion of metabolic products, ketone bodies, was quantitatively insignificant. The transport process was accompanied by increased Na, K, and water absorption, by luminal alkalinization due to bicarbonate accumulation, and by a fall in lumen PCO2. The results are consistent with the existence of two mechanisms for colonic SCFA absorption: first, nonionic diffusion of protonated SCFA involving consumption of luminal CO2; this process accounts for about 60% of total SCFA absorption; and second, cellular uptake by ionic diffusion of the Na or K salt of the SCFA.
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PMID:Absorption of short-chain fatty acids by the colon. 676 37

The use of a few microcuries of 14C labelled molecules with very short biological half-life for breath-tests gives no more body irradiation than 10 minutes' exposure to the sun. Yet it provides the gastroenterologist with accurate information. Detection and identification of fat malabsorption are easy when 3 labelled lipids are used. Glycine 1 14C cholate administered orally offers a simple, rapid and effective screening technique for the detection of increased bile salt deconjugation and may provide a valuable diagnostic supplement in the study of steatorrhea after ileal resection, bypass or bacterial overgrowth. The clearance of labelled aminopyrine can be decreased in hepatocellular dysfunction or increased in some alcoholic patients or in patients receiving phenobarbitone. Tracer doses of labelled ethanol were used to study the metabolism of ethanol by the liver in alcoholic patients. Chronic ingestion of alcohol stimulates the activity of microsomal drug-metabolising enzymes in both non-cirrhotic and cirrhotic patients; this response is lost in acute liver damage and in chronic alcoholic disease with severe hepatic dysfunction. The CO2-labelled breath-tests are non-invasive, effective and inexpensive. The forthcoming replacement of 14C by non-radioactive 13C or briefly radioactive 11C will render these tests even more attractive.
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PMID:[Labelled CO2 breath-tests in gastroenterology (author's transl)]. 679

Carbon isotope breath tests are often interpreted assuming a constant endogenous production of CO2 (some including calculations assuming a specific production of 9 mmol CO2/body weight per hour). We have evaluated the endogenous-CO2 production following ingestion of caloric meals varying with the range of most currently available carbon isotope breath tests. On three separate test days, fasting basal CO2 production was 8.08 +/- 0.55, 8.00 +/- 0.47, and 8.23 +/- 0.48 mmol/kg-hr (mean +/- s.e.m.), with a range 6-11 mmol/kg-hr. Administration of zero and 100 kcal led to no significant change from the basal CO2 production. In contrast, administration of 200 kcal or more led to significant elevation of endogenous CO2 production both by normal subjects and by subjects with nutrient malabsorption. This phenomenon could influence interpretation of some nonfasting isotopic CO2 breath tests; it deserves further evaluation.
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PMID:Alteration of CO2 production during nonfasting isotopic CO2 breath tests: concise communication. 679 20

Breath tests rely on the measurement of gases produced in the intestine, absorbed, and expired in the breath. Carbohydrates, such as lactose and sucrose, can be administered in physiologic doses; if malabsorbed, they will be metabolized to hydrogen by colonic bacteria. Since hydrogen is not produced by human metabolic reactions, a rise in breath hydrogen, as measured by gas chromatography, is evidence of carbohydrate malabsorption. Likewise, a rise in breath hydrogen marks the transit time of nonabsorbable carbohydrates such as lactulose through the small intestine into the colon. Simple end-expiratory interval collection into nonsiliconized vacutainer tubes has made these noninvasive tests quite convenient to perform, but various problems, including changes in stool pH, intestinal motility, or metabolic rate, may influence results. Another group of breath tests uses substrates labeled with radioactive or stable isotopes of carbon. Labeled fat substrates such as trioctanoin, tripalmitin, and triolein do not produce the expected rise in labeled breath CO2 if there is fat malabsorption. Bile acid malabsorption and small intestinal bacterial overgrowth can be measured with labeled cholylglycine or cholyltaurine. Labeled drugs such as aminopyrine, methacetin, and phenacetin can be used as an indication of drug metabolism and liver function. Radioactive substrates have been used to trace metabolic pathways and can be measured by scintillation counters. The availability of nonradioactive stable isotopes has made these ideal for use in children and pregnant women, but the cost of substrates and the mass spectrometers to measure them has so far limited their use to research centers. It is hoped that new techniques of processing and measurement will allow further realization of the exciting potential breath analysis has in a growing list of clinical applications.
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PMID:Breath tests: principles, problems, and promise. 718 Jun 96

The use of 14CO2 breath tests and fecal analyses for the detection and quantitation of intestinal malabsorption has been extensively documented in adult subjects. The use of stable isotopes has extended the range of breath test applications to include pediatric and obstetric subjects. Here we report a fecal 13C analysis that can be used in conjunction with 13CO2 breath tests. Twenty-four-hour fecal samples were collected before and after the administration of a labeled substrate. The samples were homogenized and combusted to CO2, and the 13C abundance was determined by high-precision, differential isotope ratio mass spectrometry. The isotopic variation between successive 24 hr fecal samples was 0.6 0/00 (0.0006 atom percent). This variation limited the sensitivity of the fecal analysis to 13 mumol of 13C label per mold of fecal carbon. Simultaneous cholyglycine 13CO2 breath tests and fecal assays were performed in five children. One child with bacterial overgrowth had an abnormal breath test and a normal fecal test. Of three children with ileal dysfunction, only one had an abnormal breath test, whereas the fecal test was abnormal in all three, Both the breath test and fecal test were abnormal for a child who had undergone an ileal resection. Both tests were normal for a child with ulcerative colitis.
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PMID:Fecal 13C analysis for the detection and quantitation of intestinal malabsorption. Limits of detection and application to disorders of intestinal cholylglycine metabolism. 746 74

Fructose malabsorption is characterized by the inability to absorb fructose efficiently. As a consequence fructose reaches the colon were 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 consequence and can be seen in about 50% of fructose malabsorbers. Having made the observation that persons with fructose malabsorption very often seem to present not only with signs of irritable bowel syndrome but also with signs of pre-menstrual syndrome and mental depression, it was of interest to establish whether such an association could be demonstrated in patients. Fifty-five adults with gastrointestinal complaints of unknown origin (12 males, 43 females) were analyzed by measuring breath hydrogen concentrations after an oral dose of 50 g fructose and were classified as normals or fructose malabsorbers according to their breath H2 concentrations. All patients filled out a Beck s depression inventory - questionnaire. Fructose malabsorption was detected in 36 of 55 individuals (65.5%). Subjects with fructose malabsorption (DeltaH2 concentrations >10 p.p.m. after fructose load) showed a significantly higher score in the Beck s depression inventory than normal fructose absorbers. This was true especially for females. Fructose malabsorption may play a role in the development of depressed mood. Fructose malabsorption should be considered in patients with symptoms of major depression or pre-menstrual syndrome. Further studies are needed to clarify the background of this association.
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PMID:Fructose malabsorption is associated with early signs of mental depression. 962 Aug 91

In growth studies on rats, the ketohexose D-tagatose has been shown to contribute no net metabolizable energy, and a pronounced thermic effect of the sugar has been suggested to account for the absence of energy. In a double-blind and balanced cross-over design, we measured 24-h energy expenditure in eight normal weight humans in a respiration chamber during the consumption of 30 g D-tagatose or 30 g sucrose/d. Metabolic measurements were performed before and after a 2-wk adaptation period with a 30-g daily intake of the test sugar. Total 24-h energy expenditure and hour-by-hour profile were unaffected by the test sugar. The nonprotein respiratory exchange ratio (RERnp) was similar during consumption of D-tagatose and sucrose. However, the effect on RERnp due to CO2 produced by fermentation of D-tagatose could not be quantified in this study. A significant increase in 24-h H2 production (35%) during D-tagatose administration suggests a substantial malabsorption of the sugar. We found no effects of the 2-wk adaptation period on the measured gas exchange variables. Significantly lower fasting plasma insulin and triglyceride concentrations were observed during D-tagatose administration compared with the sucrose period. No effects of D-tagatose on body weight and composition were seen, but the perception of fullness 2.5 h after the sugar load was greater with D-tagatose. In conclusion, this study does not suggest a pronounced thermic effect of D-tagatose, and other mechanisms seem to be required to explain its lack of net energy.
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PMID:D-Tagatose, a stereoisomer of D-fructose, increases hydrogen production in humans without affecting 24-hour energy expenditure or respiratory exchange ratio. 973 8

Lactose malabsorption is characterized by a deficiency of mucosal lactase. As a consequence, lactose reaches the colon where it is broken down by bacteria to short-chain fatty acids, CO2, and H2. Bloating, cramps, osmotic diarrhea, and other symptoms of irritable bowel syndrome are the consequence and can be seen in about 50% of lactose malabsorbers. Having made the observation that females with lactose malabsorption not only showed signs of irritable bowel syndrome but also signs of premenstrual syndrome and mental depression, it was of interest to establish whether a statistical correlation existed between lactose malabsorption and mental depression. Thirty female volunteers were analyzed by measuring breath H2 concentrations after an oral dose of 50 g lactose and were classified as normals or lactose malabsorbers according to their breath H2 concentrations. All patients filled out a Beck's depression inventory questionnaire. Of the 30 female volunteers, six were lactose intolerant (20%) and 24 were normal lactose absorbers (80%). Subjects with lactose malabsorption showed a significantly higher score in the Beck's depression inventory than normal lactose absorbers did. The data thus suggest that lactose malabsorption may play a role in the development of mental depression. In lactose malabsorption high intestinal lactose concentrations may interfere with L-tryptophan metabolism and 5-hydroxytryptamine (serotonin) availability. Lactose malabsorption should be considered in patients with signs of mental depression.
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PMID:Lactose malabsorption is associated with early signs of mental depression in females: a preliminary report. 982 44

Fructose malabsorption is characterized by the inability to absorb fructose efficiently. Consequently fructose reaches the colon and is broken down by bacteria to short-fatty-acids, CO2 and H2. Recently we found that fructose malabsorption was associated with signs of depression. It was therefore of interest to find out whether fructose malabsorption is associated with abnormal tryptophan metabolism. Breath hydrogen concentrations were measured in 50 after an oral dose of 50 g fructose allowing to classify them as normals (n = 15) or fructose malabsorbers (n = 35). Blood samples were taken for tryptophan and kynurenine measurements. Fructose malabsorbers showed significantly lower plasma tryptophan concentrations and significantly higher depression scores compared to normals. Fructose malabsorption is associated with lower tryptophan levels which may play a role in the development of depressive disorders.
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PMID:Fructose malabsorption is associated with decreased plasma tryptophan. 1072 Oct 40


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