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PubMed1988

Lactitol vs. lactulose in the treatment of chronic recurrent portal-systemic encephalopathy.

To compare the efficacy and patient acceptability of lactitol vs. lactulose in chronic recurrent portal-systemic encephalopathy (PSE), 25 cirrhotic patients with a history of repeated episodes of hepatic encephalopathy who required chronic administration of lactulose were included in a controlled cross-over clinical trial in which patients received, at random, lactitol (at an initial dosage of 10 g/6 h) or lactulose (15 ml/6 h, 66% w/v, containing 10 g of lactulose) during a 3 month period and then crossed-over to the alternative treatment for the following 3 months. Doses were adjusted to obtain two bowel movements per day. During the study period the daily protein intake was 40-60 g. Clinical and analytical data (including ammonia levels) were obtained, an EEG and the number connection test were performed and the PSE index was determined before treatment and monthly until the end of the treatment. No significant differences were found between the effects of lactitol and lactulose on the neurological and biological parameters, suggesting that the two treatments could be considered as equally effective. Lactitol was significantly better tolerated than lactulose (P = 0.02), the taste of which was assessed as being too sweet and provoking nausea. In conclusion, lactitol is a good alternative to lactulose for patients with chronic recurrent PSE, especially in those who do not tolerate the excessive sweetness of lactulose.

Clinical Trials as Topic↗
PubMed1995

Protective role of lactulose in intestinal carcinogenesis.

Primary bile acids are converted to carcinogenic secondary bile acids by colonic bacteria when the colonic pH is high. Therefore acidification of the luminal contents may reduce the cancer risk. The ability of lactulose to reduce colonic pH, secondary bile acid production, mucosa crypt cell production rate and tumour formation was measured in a rat model of intestinal carcinogenesis. Eighty Wistar rats were divided into four groups receiving normal diet alone or with lactulose, azoxymethane or both azoxymethane and lactulose. The addition of lactulose was associated with a significant fall in small intestinal and colonic pH. Lactulose was associated with a sharp rise in the secondary to primary bile acid ratio. The crypt cell production rate fell significantly with lactulose. The addition of lactulose was associated with a significantly reduced tumour yield in small intestine but not in colon. Lactulose therefore can reduce this is of no value in humans at risk of developing colorectal carcinoma.

Acid-Base Imbalance↗
PubMed2001

Dietary lactulose decreases apparent nitrogen absorption and increases apparent calcium and magnesium absorption in healthy dogs.

To study the effect of lactulose on the route of nitrogen excretion, we fed six healthy, adult dogs on diets containing either 0, 1 or 3 g lactulose/MJ metabolizable energy according to a 3 x 3 Latin square design. The results were analysed to identify statistically significant linear trend effects of lactulose. Faecal pH was significantly lowered by lactulose. Faecal ammonium and nitrogen excretion tended to be raised by lactulose feeding whereas urinary urea excretion was significantly reduced. Lactulose feeding significantly lowered apparent nitrogen digestibility. It is concluded that lactulose feeding shifts nitrogen excretion from urine to faeces in dogs which may be beneficial for liver patients. The data are in line with the concept that lactulose stimulates bacterial growth in the colon which in turn enhances faecal nitrogen excretion and lowers the entry of colonic ammonia into the bloodstream, leading to a lesser workload for the liver and less urinary nitrogen excretion. Lactulose consumption was also found to produce a dose-dependent increase in the apparent absorption of calcium and magnesium, but not phosphorus.

Animals↗
PubMed2004

Investigation on the precaecal and faecal digestibility of lactulose and inulin and their influence on nutrient digestibility and microbial characteristics.

This study was conducted to determine the pre-caecal and faecal digestibility of lactulose and inulin and the influence of these substances on nutrient digestibility and microbial characteristics. In metabolic trials three of six male growing pigs (German Landrace x Pietrain) were fitted with an ileo-rectal anastomosis (IRA) in end-to-end technique with preserved ileo-caeco-colic valve. The metabolic trials were conducted from day 21-63 after surgery. The remaining pigs were used as intact partners (IN) for the IRA pigs. The experimental diets, based on corn, wheat, barley and soybean meal, were supplemented with either 1.5% lactulose or 2% inulin in replacement of diatomaceous earth (control). Pre-caecal digestibility of lactulose and inulin was assessed to be 79 and 98%, respectively. faecal digestibility was determined as 100%. The supplementation of lactulose and inulin had only minor effects on the pre-caecal and faecal digestibility of nutrients. Significant differences in nutrient digestibility were obvious between IRA and IN pigs, whereas the IRA pigs showed lower digestibility values with the exception of ether extracts (EE). Bacterial population in the digesta of IRA and IN pigs were not affected by the experimental diets except the concentration of gram-negative anaerobes, which inclined when the IRA pigs received the lactulose diet. The pH of chyme was significantly lower than the pH of faeces, however the pH was unaffected by the different supplemented diets. The concentration of volatile fatty acids (VFA) in pre-caecal chyme decreased significantly when IRA pigs received the lactulose supplemented diet whereas VFA in faeces were unaffected by the supplementation. IRA pigs administered with lactulose excreted more N via the urine, but the nitrogen balance remained unaffected. From the present investigation it can be concluded that lactulose and inulin did only partly or scarcely fulfill the expectation of acting as prebiotics in pigs.

Anastomosis, Surgical↗
PubMed1997

Effects of lactulose on nitrogen metabolism.

Lactulose is the most frequently utilized agent in the treatment of hepatic encephalopathy because of its efficacy and the fact that it has few serious side effects. How this non-absorbable disaccharide works has been a matter of controversy, but evidence suggests that metabolism by the enteric flora is necessary for its mechanism of action. When the intestinal flora metabolizes lactulose, bacterial incorporation of nitrogen increases, as does the bacterial mass. The presence of a carbohydrate and the acidic environment caused by the production of organic acids also act to reduce the breakdown of other nitrogen-containing compounds to ammonia and other potential cerebral toxins. The administration of lactulose to humans causes an increase in fecal nitrogen, but very little increase in ammonia nitrogen. Most of the nitrogen is contained in the fecal bacterial and the soluble fractions of stool. The administration of lactulose causes a reduction in the urea production rate consistent with a reduced entry of ammonia into portal blood, but it does not appear to directly inhibit urea degradation. Other non-absorbable saccharides, particularly those contained in dietary fiber, appear to have effects similar to those of lactulose. There is some evidence that neomycin can be given with lactulose to cause an additive effect in the treatment of hepatic encephalopathy. This effect is most prominent in patients who have not responded adequately to lactulose alone. At this point, the other antibiotics studied do not appear to have additive effects with lactulose.

Ammonia↗
PubMed2005

Effects of lactulose and polyethylene glycol on colonic transit.

BACKGROUND: The effects of lactulose and polyethylene glycol on colonic transit are poorly established. AIM: To assess the effects of these laxatives on colonic transit in normal subjects. METHODS: Colonic transit (mean residence time, cumulative counts in stool, counts remaining in the proximal or distal colon) was measured scintigraphically in normal subjects on the second and third day of a 3-day ingestion of 67-134 g/day lactulose, or 59 g/day polyethylene glycol. RESULTS: At similar stool weight (lactulose: 653 +/- 120 g/day; polyethylene glycol: 522 +/- 66 g/day), transit was significantly slower during 99 g/day lactulose when compared with 59 g/day polyethylene glycol; this was most pronounced in the distal colon (mean residence time: lactulose - 403 +/- 55 min; polyethylene glycol - 160 +/- 41.9 min). Short chain fatty acid concentration in 24-h stool correlated significantly with counts remaining in the distal colon at 12 h (r = 0.79, P = 0.001). Increasing lactulose doses were significantly associated with increasing stool weight (r = 0.79) and shorter mean residence time in the total (r = -0.56) and distal colon (r = -0.64). The sum of faecal carbohydrates plus short chain fatty acids was associated with stool weight (r = 0.95, P < 0.001). CONCLUSION: Lactulose accelerates colonic transit. However, compared with polyethylene glycol, transit during lactulose is prolonged.

Adult↗
PubMed1993

Chronic constipation in long stay elderly patients: a comparison of lactulose and a senna-fibre combination.

OBJECTIVES: To compare the efficacy and cost effectiveness of a senna-fibre combination and lactulose in treating constipation in long stay elderly patients. DESIGN: Randomised, double blind, cross over study. SETTING: Four hospitals in Northern Ireland, one hospital in England, and two nursing homes in England. SUBJECTS: 77 elderly patients with a history of chronic constipation in long term hospital or nursing home care. INTERVENTION: A senna-fibre combination (10 ml daily) or lactulose (15 ml twice daily) with matching placebo for two 14 day periods, with 3-5 days before and between treatments. MAIN OUTCOME MEASURES: Stool frequency, stool consistency, and ease of evacuation; deviation from recommended dose; daily dose and cost per stool; adverse effects. RESULTS: Mean daily bowel frequency was greater with the senna-fibre combination (0.8, 95% confidence interval 0.7 to 0.9) than lactulose (0.6, 0.5 to 0.7; t = 3.51 p < or = 0.001). Scores for stool consistency and ease of evacuation were significantly higher for the senna-fibre combination than for lactulose. The recommended dose was exceeded more frequently with lactulose than the senna-fibre combination (chi 2 = 8.38, p or = 0.01). As an index of the standard daily dose, the dose per stool was 1.52 for lactulose and 0.97 for the senna-fibre combination, at a cost per stool of 39.7p for lactulose and 10.3p for senna-fibre. Adverse effects were no different for the two treatments. CONCLUSIONS: Both treatments were effective and well tolerated for chronic constipation in long stay elderly patients. The senna-fibre combination was significantly more effective than lactulose at a lower cost.

Aged↗
PubMed2004

PEG 3350 (Transipeg) versus lactulose in the treatment of childhood functional constipation: a double blind, randomised, controlled, multicentre trial.

BACKGROUND: Recently, polyethylene glycol (PEG 3350) has been suggested as a good alternative laxative to lactulose as a treatment option in paediatric constipation. However, no large randomised controlled trials exist evaluating the efficacy of either laxative. AIMS: To compare PEG 3350 (Transipeg: polyethylene glycol with electrolytes) with lactulose in paediatric constipation and evaluate clinical efficacy/side effects. PATIENTS: One hundred patients (aged 6 months-15 years) with paediatric constipation were included in an eight week double blinded, randomised, controlled trial. METHODS: After faecal disimpaction, patients <6 years of age received PEG 3350 (2.95 g/sachet) or lactulose (6 g/sachet) while children > or =6 years started with 2 sachets/day. Primary outcome measures were: defecation and encopresis frequency/week and successful treatment after eight weeks. Success was defined as a defecation frequency > or =3/week and encopresis < or =1 every two weeks. Secondary outcome measures were side effects after eight weeks of treatment. RESULTS: A total of 91 patients (49 male) completed the study. A significant increase in defecation frequency (PEG 3350: 3 pre v 7 post treatment/week; lactulose: 3 pre v 6 post/week) and a significant decrease in encopresis frequency (PEG 3350: 10 pre v 3 post/week; lactulose: 8 pre v 3 post/week) was found in both groups (NS). However, success was significantly higher in the PEG group (56%) compared with the lactulose group (29%). PEG 3350 patients reported less abdominal pain, straining, and pain at defecation than children using lactulose. However, bad taste was reported significantly more often in the PEG group. CONCLUSIONS: PEG 3350 (0.26 (0.11) g/kg), compared with lactulose (0.66 (0.32) g/kg), provided a higher success rate with fewer side effects. PEG 3350 should be the laxative of first choice in childhood constipation.

Adolescent↗
PubMed1995

Evaluation of intestinal permeability in patients with inflammatory bowel disease using lactulose and measuring antibodies to lipid A.

This study looked at the intestinal permeability and the immune response to enteric bacterial antigens in patients with inflammatory bowel disease (IBD). They were evaluated by using a lactulose tolerance test and measuring blood anti-lipid A antibody concentrations, respectively. The lactulose tolerance tests were performed 22 times in 14 patients with Crohn's disease (CD), 19 times in 12 patients with ulcerative colitis (UC), and 12 times in 12 healthy controls. Blood lactulose concentrations were measured after oral administration every two hours for eight hours, also blood C reactive protein concentrations and anti-lipid A antibody concentrations were measured just before lactulose administration. Blood lactulose concentrations were significantly higher in patients with CD than in the controls from two to eight hours after administration, while in UC they were significantly higher than in the controls from six to eight hours. Maximum blood lactulose concentrations in each tolerance test in patients with the active phase significantly exceeded those in the inactive phase of either CD or UC. A significant correlation was also seen between the maximum blood lactulose concentrations and the C reactive protein concentrations. Blood anti-lipid A antibody concentrations in patients with CD were significantly higher than in the controls as well as in patients with UC in immunoglobulin (Ig) A class and IgG class. In UC they were significantly higher than in the controls in IgA class. But, they were not related to the severity of the disease of either CD or UC, and not correlated significantly with the maximum blood lactulose concentrations in either CD or UC. The intestinal permeability and the immune response to enteric bacterial antigens in patients with inactive CD were significantly increased over those in the controls as well as in patients with inactive UC. These findings suggest that an increase of the intestinal permeability and that of producing antibodies to enteric bacterial antigens are both important for the pathogenesis of IBD, and that the characteristics of CD and UC differ.

Adolescent↗
PubMed2005

Colonic fermentation from lactulose inhibits lipolysis in overweight subjects.

One of the strategies to prevent insulin resistance is to reduce circulating free fatty acids (FFA). The aim of this study is to assess the effect of an oral lactulose load on fatty acid metabolism in overweight subjects. Eight overweight subjects received a primed constant intravenous infusion of [1-(13)C]acetate and of [1,1,2,3,3-(2)H(5)]glycerol for 9 h. After 3 h of tracer infusion, patients ingested 30 g lactulose, or saline solution. Arterialized blood samples were collected every 20 min. Basal plasma concentrations of acetate were similar before and between oral treatments as well as glycerol and FFA concentrations. Plasma acetate turnover was 11.4 +/- 2.4 vs. 10.7 +/- 1.4 micromol.kg(-1).min(-1) [not significant (NS)], and plasma glycerol turnover was 3.8 +/- 0.4 vs. 4.8 +/- 1.9 micromol.kg(-1).min(-1) (NS). After lactulose ingestion, acetate concentration increased twofold and then decreased to baseline. Acetate turnover rate increased to 15.5 +/- 2.2 micromol.kg(-1).min(-1) after lactulose treatment, whereas it was unchanged after saline treatment (10.3 +/- 2.2 micromol.kg(-1).min(-1), P < or = 0.0001). In contrast, FFA concentrations decreased significantly after lactulose ingestion and then increased slowly. Glycerol turnover decreased after lactulose ingestion compared with saline, 2.8 +/- 0.4 vs. 3.5 +/- 0.3 micromol.kg(-1).min(-1) (P < or = 0.05). A significant negative correlation was found between glycerol and acetate turnover after lactulose treatments (r = -0.78, P < or = 0.02). These results showed in overweight subjects a short-term decrease in FFA level and glycerol turnover after lactulose ingestion related to a decrease of lipolysis in close relationship with an increase of acetate production.

Acetates↗
PubMed1996

Lactulose and combination therapy of hepatic encephalopathy: the role of the intestinal microflora.

Lactulose is the most frequently utilized agent in the treatment of hepatic encephalopathy because of its efficacy and the fact that it has few serious side effects. How this nonabsorbable disaccharide works has been a matter of controversy, but evidence suggests that metabolism by the enteric flora is necessary for its mechanism of action. When the intestinal flora metabolized lactulose, bacterial incorporation of nitrogen increases as does the bacterial mass. The presence of a carbohydrate and the acidic environment caused by the production of organic acids also act to reduce the breakdown of other nitrogen-containing compounds to ammonia and other potential cerebral toxins. The administration of lactulose to humans causes an increase in fecal nitrogen, but very little increase in ammonia nitrogen. Most of the nitrogen is contained in the fecal bacterial and the soluble fractions of stool. The administration of lactulose causes a reduction in the urea production rate consistent with a reduced entry of ammonia into portal blood, but it does not appear to directly inhibit urea degradation. Other nonabsorbable saccharides, particularly those contained in dietary fiber, appear to have effects similar to those of lactulose. There is some evidence that neomycin can be given with lactulose to cause an additive effect in the treatment of hepatic encephalopathy. This effect is most prominent in patients who have not responded adequately to lactulose alone. At this point, the other antibiotics studied do not appear to have additive effects with lactulose.

Ammonia↗
PubMed1997

Lactulose, disaccharides and colonic flora. Clinical consequences.

Lactulose is one of the most frequently utilised agents in the treatment of constipation and hepatic encephalopathy because of its efficacy and good safety profile. The key to understanding the possible modes of action by which lactulose achieves its therapeutic effects in these disorders lies in certain pharmacological phenomena: (a) lactulose is a synthetic disaccharide that does not occur naturally; (b) there is no disaccharidase on the microvillus membrane of enterocytes in the human small intestine that hydrolyses lactulose; and (c) lactulose is not absorbed from the small intestine. Thus, the primary site of action is the colon in which lactulose is readily fermented by the colonic bacterial flora with the production of short-chain fatty acids and various gases. The purpose of this review is to focus on some pertinent basic aspects of the clinical pharmacology of lactulose and to discuss the possible mechanisms by which lactulose benefits patients with constipation and hepatic encephalopathy.

Animals↗
PubMed1998

Transitory laxative threshold of trehalose and lactulose in healthy women.

The transitory laxative threshold of a partially digestible disaccharide, trehalose, and an undigestible disaccharide, lactulose, was estimated by the dose-response relation between the test substance and the prevalence of diarrhea in 20 healthy female subjects. The subjects ingested several indicated amounts of trehalose or lactulose once daily 2 to 3 h after a meal. The intake of the test substance was stopped at the dose level that caused diarrhea or when the dose reached the maximal level. A record of physical conditions, gastrointestinal symptoms, and fecal conditions was made by all subjects before and after each ingestion of the test substance. Half the subjects experienced no diarrhea even with the ingestion of the maximal dose level (60 g) of trehalose in this study, and the ingestion of up to 40 g of lactulose caused diarrhea in 75% of all subjects. Abdominal symptoms such as flatus, distension, and borborygmus appeared at high prevalence with lactulose and trehalose ingestion, and the effect of lactulose was significantly stronger than that of trehalose at the same dose level (p < 0.05). The quantity of trehalose and lactulose that induced diarrhea differed greatly from person to person. The transitory laxative threshold was estimated as 0.65 g/kg body weight for trehalose and 0.26 g/kg body weight for lactulose by using the regression equation between the dose levels of the test substances and the cumulative incidence of diarrhea. These results suggest that it would be quite acceptable to administer trehalose up to 33 g and lactulose up to 13 g in a person weighing 50 kg.

Abdomen↗
PubMed1990

[The H2-lactulose breath test in the diagnosis of intestinal transit time].

The H2-Lactulose breath test is used to detect small bowel bacterial overgrowth but mainly to evaluate the orocoecal transit time (OCTT) in man. The result of the H2-breath test is influenced by several intestinal and extraintestinal factors that cause a large variability of normal values. By reviewing the possible influencing factors of the breath tests we try to make a contribution to a better judgement of the results as the H2-lactulose breath-test is a simple noninvasive and non-expensive screening in the investigation of gastrointestinal disorders. For evaluating the better dosage of lactulose in gastroenterological routine diagnostic we designed a prospective study. The test was performed in 12 healthy volunteers by ingestion of 10 g and 20 g lactulose to quantitate the OCTT and to evaluate it in normal conditions. We found that the length of transit is related to the dose of lactulose. OCTT was 97.1 +/- 22.4 min. after ingestion of 10 g lactulose, and significantly shorter, 57.1 +/- 16.6 min. after ingestion of 20 g lactulose (p less than or equal to 0.01). The lower dose of lactulose is more suitable for routine diagnostic because of better acceptance despite slower transit time.

Adult↗
PubMed1979

The effect of lactulose on urea metabolism and nitrogen excretion in cirrhotic patients.

The mechanism of action of lactulose is not known, although in vitro evidence suggests that lactulose may increase ammonia utilization and decrease ammmonia production by gut flora. If these changes occur in patients, they should be reflected in altered urea metabolism and nitrogen excretion. In seven studies conducted in 6 cirrhotic patients, the effects of lactulose on the kinetics of urea metabolism and nitrogen excretion were determined. Lactulose caused a fall in urea production (-24%, P less than 0.005) that was reflected in a decrease in both urea degradation and urinary urea excretion. Likewise, lactulose caused a decrease in the total body urea pool. The fall in urinary urea was accompanied by a large (two- to threefold) increase in stool nitrogen that was of a similar magnitude of the fall in urinary urea. Although urea degradation fell after lactulose, the intestinal (extrarenal) clearance of urea did not, indicating that the fall in urea degradation was due to the observed fall in the urea pool. The results indicate that: (a) Lactulose decreases urea production by increasing the fecal output of nitrogen, a finding compatible with altered ammonia metabolism by gut flora. (b) Lactulose decreases urea degradation, although this effect is primarily the result of a fall in the urea pool and cannot be attributed to an inhibition of urea breakdown in the gut lumen.

Aged↗
PubMed1995

Comparison of lactulose and inulin as reference standard for the study of resistant starch fermentation using hydrogen breath test.

Disaccharide lactulose is commonly used as a standard to quantitate the colonic fermentation of undigested sugars by means of H2 breath measurements. However, its high hydrogen production rate during fermentation may make it inappropriate for mimicking the fermentation of more complex carbohydrates, such as starch. Indigestible carbohydrates with a higher molecular weight might be more suitable than lactulose as a standard in H2 breath studies of starch digestibility. To test this hypothesis, we measured H2 breath in 8 healthy volunteers after a standard meal supplemented with 5 g or 10 g of lactulose or inulin, an indigestible oligosaccharide with an average degree of polymerization 4.5 times higher than that of lactulose. The results were then compared with those obtained after a standard meal containing a known amount (6.1 g) of resistant starch from high-amylose corn starch. Median H2 breath excretion per gram of reference carbohydrate was lower after the 5 g dose of inulin than after the 5 g dose of lactulose (19.1 vs 26.6 ppm x h x g-1; Wilcoxon's rank test p = 0.021) but similar after the two 10 g doses (inulin 22.4; lactulose 23.6; p = 0.234). Median H2 breath excretion per gram of resistant starch was significantly lower than that for both lactulose and inulin (p < 0.02), being 4.7 ppm x h x g-1. In vitro fermentation for 8 hrs with fecal homogenate showed similar mean hydrogen production rates for inulin and lactulose (30.5 vs 27.7 mL/mg fermented carbohydrate), and a significantly lower rate for starch (9.1 mL/mg) (n = 7; ANOVA p = 0.0007).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Colonic transit times and the effect of lactulose or lactitol in hospitalized patients.

OBJECTIVE: To investigate whether a small dose (10 g per day) of a laxative (liquid lactulose, crystallized lactulose, or crystallized lactitol) can prevent the slow colonic transit associated with the physical inactivity of hospitalization. DESIGN: Patients were randomly allocated to one of four groups: control, liquid lactulose, crystallized lactulose or crystallized lactitol, and the average of mean colonic transit times in these groups was compared. SETTING: Gastroenterologic Unit, Hospital dos Covoes, Coimbra, Portugal. PATIENTS: Patients with normal bowel movements, admitted to hospital for the investigation of conditions not associated with constipation or diarrhoea, were allocated to one of the four treatment groups and had their mean colonic transit times studied after hospitalization using radiopaque markers and abdominal radiographs. Each study group had 18 patients. During the study, each patient was given a normal diet and no drugs except the relevant laxative. RESULTS: The average of the mean colonic transit times in each of the four groups were: 52.16 h [95% confidence interval (CI) 39.42-64.84] for controls; 22.45 h (95% CI 13.84-31.06) in the liquid lactulose group; 24.05 (95% CI 12.13-35.97) in the crystallized lactulose group; and 35.95 (95% CI 23.82-48.08) in the crystallized lactitol group. The differences were statistically significant for the two lactulose groups. The study of the mean colonic regional transit times showed that these differences related to transit in the right colon. CONCLUSIONS: A small dose of lactulose (either liquid or crystallized) was effective in preventing slow colonic transit and constipation in hospitalized patients without causing unwanted symptoms. The slow transit affected mainly the right colon, and it was in this region that the laxative had effect.

Adult↗
PubMed1993

Prevalence and consistency of low breath H2 excretion following lactulose ingestion. Possible implications for the clinical use of the H2 breath test.

The clinical use of the H2 breath test is limited by the finding that a variable fraction of the population fails to excrete appreciable H2 during colonic carbohydrate fermentation. Therefore, we assessed the ability to increase breath H2 excretion in 371 patients (224 female, 147 male) by administering the nonabsorbable sugar lactulose. Following 12g of lactulose, 27% of 94 patients did not increase their breath H2 concentration over 20 ppm and were considered low H2 excretors. Ingestion of 20 g of lactulose in 277 patients yielded a frequency of low H2 excretors of 14%. Six of 10 patients that were low H2 excretors after 12g of lactulose increased their breath H2 levels over 20 ppm when tested with 20g. In 35 patients tested with the same amount of lactulose on two separate occasions, the subject frequently altered his or her H2 producing status over a period of a few weeks. Low H2 excretors had a significantly higher breath CH4 concentration, both fasting (22 +/- 34 ppm) and after lactulose (51 +/- 58 ppm) compared to the remaining patients (5 +/- 13 ppm and 16 +/- 40 ppm, respectively). While the mean age of low excretors (54 +/- 17 years) was significantly higher than the others (44 +/- 17 years), no difference was found for sex prevalence and stool pH. This study demonstrates that respiratory H2 excretion following lactulose ingestion is not consistent and suggests that the application of too restrictive criteria could lead to improper interpretation of the H2 breath test.

Adult↗