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The impact of HIV infection on lactose absorptive capacity
Journal of Infection (1997) 35.31-35
The Impact of HIV Infection on Lactose Absorptive Capacity G. R. Corazza, L. Ginaldi, N. Furia, G. Marani-Toro 1, D. Di Giammartino 1 and D. Quaglino Department of Internal Medicine, University of L'Aquila, Via S.Sisto 22/E, 67100 L'Aquila, Italy, and 1Division of Infectious Diseases, "Ospedale Civile", Teramo, Italy Forty HIV-infected adult patients at different disease stages and 44 healthy volunteers were evaluated for lactose malabsorption using the hydrogen breath test after 20 g lactose ingestion. All subjects were previously tested for breath hydrogen (H2) excretion after 12 g lactulose ingestion. The presence of intestinal superinfections, gastrointestinal symptoms and the intensity of clinical intolerance after lactose load were accurately searched in each patient. The cumulative H2 excretion after lactulose did not significantly differ between the different groups studied. The prevalence of lactose malabsorption turned out to be significantly higher (P<0.001) in HIV-infected patients (70%) than in controls (34%). Moreover, in patients in more advanced disease stages the degree of lactose malabsorption was significantly greater than in patients at earlier disease stages, who did not differ from healthy volunteers. Furthermore the degree of lactose intolerance was significantly greater (P<0.001) in symptomatic patients than in those without intestinal symptoms and in healthy volunteers, while no significant difference was observed between these latter groups. The results here demonstrate the negative impact of HIV infection on lactose absorptive capacity in adult patients, particularly marked in more advanced stages of the disease, suggesting that, in addition to the presence of the virus alone, other factors may contribute to determine the enterokinetic alterations responsible for lactase deficiency.
Introduction Symptoms of malabsorption may frequently occur not only in patients with advanced HIV infection but also in the early stages of the disease. ~ In these cases malabsorption is considered a secondary event to the socalled HIV-associated enteropathy, 2-5 histologically characterized by partial villous atrophy 6 and mucosal inflammation. 7 The finding that HIV has been identified by various techniques either in crypt 8 or villous enterocytes 9 supports the theory that HIV by itself, even in the absence of opportunistic diseases or secondary malignancies, may have a role in the development of this enteropathy. Because a low lactase activity has been demonstrated in HIV-infected patients, 6'9 it is possible that lactose malabsorption may be responsible for some of the intestinal symptoms. Lactose malabsorption has been reported in adult patients with various stages of HIV infection by hydrogen breath test/''9 These studies, however, are subject to criticisms because they have been carried out on a limited number of patients and because the load of 50 g of lactose represents a non-physiological dose for a great number of individuals. 1° Furthermore, in these Address correspondence to Dott. L. Ginaldi. Accepted for publication 19 November 1996.
0163-4453/97/040031 +05 $12.00/0
investigations the capacity of patients to excrete appreciable H2 amounts following lactulose ingestion was not previously tested. The purpose of this study was to evaluate prevalence and degree of malabsorption of a more physiological dose of lactose in an adequate number of adult patients in various stages of the disease, in whom the capacity to produce hydrogen had been previously tested on the basis of breath H2 excretion after lactulose ingestion.
Materials and Methods Patients Forty-two HIV seropositive patients and 45 HIV-negative healthy volunteers, matched for sex and age with the patients, were enrolled in the study. Of the patients, 29 were males and 13 females, ranging in age from 16 to 45 (median 29.9). Twenty-six subjects had a history of intravenous drug abuse, three were homosexual men, two were haemophiliacs and 11 were heterosexual. The HIV infection was diagnosed by the ELISA test and confirmed by Western blot analysis for viral antibodies in all patients. The presehce of intestinal symptoms (diarrhoea, vomiting, abdominal pain, weight loss) was accurately © 1997 The British Societyfor the Study of Infection
32
G.R. Corazza e t al,
searched in all patients. Diarrhoea was defined as more t h a n two loose bowel actions per day for 2 weeks, and weight loss as a loss of at least 10% of body weight, n A search for intestinal pathogens was systematically performed and included stool cultures by means of standard microbiological cultivation assays for Salmonella enteritidis, shigella, Yersinia enterocolitica, Campylobacter jejuni, Enterotoxigenic enterobacteria, rotavirus and adenovirus. Stools were also examined for ova and parasitic agents, including Cryptosporidium and Isospora belli. Stool cultures and smears for Mycobacterium were also performed. Patients with persistent diarrhoea and/or gastrointestinal symptoms, in which initial stool studies did not show a pathogen, underwent endoscopy with biopsy for cytomegalovirus or microsporidian infections. All patients underwent a complete clinical evaluation including a t h o r o u g h historical and physical examination. The recommendations of the Centers for Disease Control 12 were followed to define the stage of disease. An informed consent was obtained from all of the patients and controls taking part in the study.
Breath Hydrogen analysis None of the patients or controls was undergoing antibiotics or cytostatic drugs, and none of them was under the influence of drugs capable of modifying the oro-cecal transit time during the 15 days before the investigation. All subjects ate a meal of rice and meat the evening before the test 13 and then fasted for the next 12 h. Smoking and physical exercise were not permitted for 30 min before and during the test, and a m o u t h wash with 20 ml of 0.05% chlorohexidine solution preceded breath sample collection.14 Breath testing was carried out for 4 h after ingestion of test solution, is Alveolar samples were collected every 30 min using the 'two bag method'. 16 Measurement of H2 concentration was performed using a gas chromatograph dedicated to the measurement of H2 (Model 12, Ouintron, Milwaukee, WI, U.S.A.). The accuracy of the detector w a s + 2 parts per million (ppm), with a linear response range between 2 and 150 ppm. All the tests were started between 0800 and 0900 hours. Breath H2 testing after lactulose and lactose ingestion were performed with a gap of 2 days from one to the other. A dose of 12 g of lactulose (120 ml of tap water) was administered and cumulative H2 excretion was estimated by calculating the area under the curve of H2 concentration in end-expiration breath samples against time. 13 Only those patients who had breath H 2 excretion higher than l O p p m after lactulose load repeated the test with a 20 g dose of lactose (100 ml). An increase in breath H2 concentration > 2 0 p p m above
the baseline value was considered indicative of lactose malabsorption. During the 8 h after lactose ingestion, the appearance of symptoms of intolerance (meteorism, flatulence, abdominal pain, diarrhoea) was evaluated and their intensity scored according to the following criteria: absent = 0, mild = 1, moderate = 2, severe = 3. On the basis of the partial scores, a cumulative index of lactose intolerance was calculated. 17
Statistical analysis Statistical analyses of results were performed by means of non-parametric methods, including the Fisher's exact probability test, the Spearman rank correlation test and the Mann-Whitney-Wilcoxon test. Differences were considered statistically significant for P values less t h a n 0.01.
Results Of the 42 patients studied, eight were asymptomatic (ASY), nine had lymphadenopathy (LAS), 13 had AIDSrelated complex (ARC) and 12 had AIDS. Eleven of these patients (four ARC and seven AIDS) had clinical manifestations of gastrointestinal dysfunction, as evidenced by persistent diarrhoea, abdominal pain or weight loss. Microbiological evaluations showed the presence of intestinal pathogens in five of these. Cryptosporidium, Campylobactel; Mycobacterium, Cytomegalovirus and Giardia lamblia were found, respectively in four cases of AIDS and one of ARC. No identifiable enteric pathogens were found in the other symptomatic or asymptomatic patients. The aetiology of the diarrhoea or other gastrointestinal symptoms remained, therefore, undetermined in six cases. As far as H2 excretion is concerned, two patients - one with AIDS, one with ARC - and one healthy volunteer did not undergo lactose breath test because of inadequate breath Ha excretion after 12 g lactulose ingestion. Figure 1 shows that the cumulative H2 excretion after 12 g lactulose did not significantly differ between different groups studied. The proportion of lactose malabsorbers in all HIVpositive patients was 70% and significantly higher (P<0.001) than the 34% observed in healthy volunteers. All patients with evidence of intestinal superinfections had lactose malabsorption. Figure 2 shows the distribution of AH2 (ppm) values after lactose ingestion in healthy volunteers and HIVinfected patients at different disease stages. In patients with ARC and AIDS, the degree of H2 breath excretion increases gradually with progression of disease. Asymptomatic patients or those with LAS did not differ significantly
HIV Infection and Lactose Malabsorption Healthy ASY volunteers
8 000
4 000
• 1. q, 2
ARC
Healthy volunteers
AIDS 10
i!.
16 000
E
LAS
33
9 ® >
HIV patients HIV patients without with intestinal intestinal symptoms symptoms
81 7 6
• "
;
~
o
000
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--
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3
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im
~
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o -
-
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2225Z:2:22:
o~
0
1 000
2:::::::::::::
.............
L__NS '
Figure 1. H2 cumulative excretion after 12 g lactulose ingestion in healthy volunteers and HIV-infectedpatients divided according to the disease stages.
120
Healthy ASY volunteers
LAS
ARC
AIDS
o
co
•
o
110 100 90 80 70 o
E
& 60 50 <
|
40
:
30 20 I
10 0
t
&
NS
Z
•
P < 0.05 NS
- - P <
NS
P < 0.05
H
P < 0.05
0 . 0 1 - -
1
< 0.01
L _ _ p
1
P
P
<
~c_p < 0 . 0 0 1 ~
P < 0.001
'
Figure 3, Index of lactose i n t o l e r a n c e after ingestion of 2 0 g lactose in h e a l t h y v o l u n t e e r s a n d HIV-infected patients w i t h o u t a n d w i t h i n t e s t i n a l symptoms.
from healthy volunteers with regards to H2 excretion. In patients with AIDS, this excretion was found to be significantly higher than in the other groups. The prevalence of lactose malabsorption was of the order of 12.5% in ASY, 77.7% in LAS, 83.3% in ARC and 90.9% in AIDS. The open circles indicate the patients with intestinal symptoms who, as reported, belong to the ARC and AIDS groups and are all lactose malabsorbers. In Fig. 3, HIV-infected patients have been divided on the basis of the presence or absence of intestinal symptoms. The degree of lactose intolerance measured during the test and in the 8 h following in symptomatic patients was significantly greater than in asymptomatic patients and healthy volunteers. No significant difference was found between healthy volunteers and HIV patients without symptoms. In HIV-infected patients there was a positive correlation between hydrogen excretion after lactose ingestion and the symptom score of intolerance (r = 0.55; P<0.O01).
Discussion
- - J
< 0.001
•
•
-
-
0.001
Figure 2. DH2 excretion after 2 0 g lactose ingestion in h e a l t h y v o l u n t e e r s and HIV infected p a t i e n t s at different disease stages. ( O ) = patients with intestinal symptoms.
The technology employed in the present study for the evaluation of prevalence and degree of lactose malabsorption has also been used in investigations carried out in HIV-infected children. 18 2o There is general agreement that both prevalence and degree are higher in patients than in controls. Prevalence but not degree of lactose malabsorption has been incidentally reported in two small series of HIV adult patients, 6'9 but both these studies suffer from numerous pitfalls. In both, the number
34
G.R. Corazza et al.
of patients studied was extremely small, the results were not compared to those obtained from a control population, in both 50 g of lactose were given, a dose which is considered not physiological, 21'1°'22 and the ability of individual patients to raise breath H2 excretion after lactulose was not previously tested. 23 In contrast, in the present study an adequate n u m b e r of HW-infected patients has been investigated, and this has enabled a subdivision into subgroups and has therefore allowed the possibility of investigating the prevalence and degree of lactose malabsorption in the various stages of disease; the results were compared with those obtained from a group of healthy volunteers chosen at random from the general population; furthermore, 20 g of lactose were given, and this dose corresponds to a cupful of milk; and finally, lactose H2 breath test was preceded by lactulose Hi breath test both in patients and in healthy volunteers. This latter device was introduced to ascertain that all candidates were H2 excretors and also for the purpose of excluding major differences in cumulative H2 excretion between the study groups that could be related to differences in bacterial intestinal flora. Our results confirm that also in adults there is a negative impact of HIV infection on lactose absorptive capacity. Prevalence and degree of lactose malabsorption are in fact significantly greater in HIV-infected patients than in the general population, and, in the former, both are higher in the more advanced stages of the disease. Only patients with ARC and AIDS presented with intestinal symptoms at the time of enrolment in the study, and in both of these groups all symptomatic patients malabsorbed 20 g of lactose. Our findings are in agreement with the results of Zuin et al. 2° who demonstrated that children in more advanced disease stage had a higher prevalence of malabsorption of low lactose doses than did patients at earlier stages and non-infected children, while no statistically significant differences were observed with a higher standard dose. Moreover, the finding that in symptomatic patients disaccharide intolerance was significantly higher than in patients without symptoms appears to indicate that lactose malabsorption and intolerance m a y in some measure contribute to the development of intestinal symptoms in these patients. Numerous factors m a y be responsible for lactose malabsorption in HIV-infected patients. Both opportunistic infections (all five patients who were suffering from intestinal superinfections showed evidence of malabsorption and intolerance) as well as presence of the virus alone m a y be responsible for a slowing-down of enterocyte kinetics, and consequently a maturation defect in brush border enzymes. 4'24 The present study was not intended to establish which of these mechanisms could
be the cause of lactose malabsorption in our patients. However, its greater prevalence in the more advanced disease stages suggests that other factors, such as viral burden, the degree of malnutrition, 2~'26 the increasingly progressive mucosal T lymphocyte depletion, 27'24'28 all contribute, in addition to the presence of the virus itself, to develop those enterokinetic alterations responsible for lactase deficiency in HIV-infected patients.
References 1 Riecken EO, Zeitz M, Ullrich R. Non-opportunistic causes of diarrhoea in HIV infection. Baillidre's Clin Gastroenterol 1990; 4: 385403. 2 Kofler DP, Gaez HP, Lange M, Klein EB, Holt PR. Enteropathy associated with acquired immunodeficiency syndrome. Ann Intern Med 1984; 101: 421-428. 3 Gillin JS, Shike M, Alcock N et al. Malabsorption and mucosal abnormalities of the small intestine in the acquired immunodefciency syndrome. Ann Intern Med 1985; 102: 619-622. 4 Cummins AG, LaBrooy JT, Stanley DP, Rowland R, Shearman DJC. Quantitative histological study of enteropathy associated with HIV infection. Gut 1990;31: 317-321. 5 Ehrenpreis El), Patterson BK, Brainer JA et al. Histopathologic findings of duodenal biopsy specimens in HIV infected patients with and without diarrhea and malabsorption. Am J Clin Pathol 1992; 97: 21-28. 6 Ullrich R, Zeitz M, Heise W, L'age M, Hoflken G, Riecken E. Small intestinal structure and function in patients infected with human immunodeficiency virus (HIV): evidence for HIV-induced enteropathy. Ann Intern Med 1989; 111: 15-21. 7 Kotler DP, Reka S, Clayton F. Intestinal mucosal inflammation associated with human immunodeficiency virus infection. Dig Dis Sci 1993; 38: 1119-1127. 8 Nelson JA, Reynolds-Kohler C, Margaretten W, Wiley CA, Reese CE, Levy JA. Human tmmunodeficiency virus detected in bowel epithelium from patients with gastrointestinal symptoms. Lancet 1988; i: 259-262. 9 Heise C, Dandekar S, Kumar P, DupIantier R, Donovan RM, Halsted CH. Human immunodeficiency virus infection of enterocytes and mononuclear cells in human jejunal mucosa. Gastroenterology 1991; 100: 1521-1527. 10 RosadoJL, Solomons NW. Sensitivity and specificity of the hydrogen breath-analysis test for detecting malabsorption of physiologicaI doses of lactose. Clin Chem 1983; 29: 545-548. 11 Lim SG, Menzies IS, Lee CA, Johnson MA, Pounder RE. Intestinal permeability and function in patients infected with human immunodeficiency virus. A comparison with coeliac disease. Scan J GastroenteroI 1993; 28: 573-580. 12 Buehler JW, Ward JW. A new definition for AIDS surveillance. Ann Intern Med 1993; 118: 390-392. 13 Kotler DP, Holt PR, Rosenweig NS. Modification of the breath hydrogen test: increased sensitivity for the detection of the carbohydrate malabsorption. ] Lab Clin Med 1982; 100: 798-805. 14 Thompson DG, O'Brien JD, Hardie JM. Influence of the oro-pharyngeal microflora on the measurement of exaled breath hydrogen. Gastroenterolo~!l 1986; 91:853 860. 15 Corazza GR, Sorge M, Strocchi A, Lattanzi ME, Benati G, Gasbarrini G. Methodology of the Hi breath test. II. Importance of the test duration in the diagnosis of carbohydrate malabsorption. Ital J Gastroenterol 1990; 22: 303-305. 16 Corazza GR, Sorge M, Maurino E, Strocchi A, Lattanzi MC, Gasbarrini G. Methodology of the Hi breath test. I. Collection and storage for gas measurement. Ital J Gastroenterol 1990; 22: 200-204. 17 Rosado JL, Solomons NW, Lisker R, Bourges H. Enzyme replacement
HIV Infection and Lactose Malabsorption
18
19
20
21
22 23
therapy for primary adult lactase deficiency. Gastroenterology 1984; 87: 1072-1082. X/IillerTL, Orav EJ, Martin SR, Cooper ER, Mclntosh K, Winter HS. Malnutrition and carbohydrate malabsorption in children with vertically transmitted human immunodeficiency virus 1 infection. Gastroenterology 1991; 100: 1296-1302. golken RH, Hart W, Oung I, Shift C, Greenson J, Perman JA. Gastrointestinal dysfunction and disaccharide intolerance in children infected with human immunodeficiency virus. J Pediatr 1991; 118: 359-363. Zuin G, Fontana M, Monti S, Marchisio P, Beretta R Principi N. Malabsorption of different lactose loads in children with human immunodeficiency virus infection. ] Pediatr Gastroenterol Nutr 1992; 15: 408-412. Bayless TM. Lactose malabsorption, milk intolerance and symptom awareness in adults. In: Page DM, Bayless TM, eds. Lactose digestion, clinical and nutritional implications. Baltimore: John Hopkins University Press, 1981: 117-123. Smith TM, Kolars JC, Savaiano DA, Levitt MD. Absorption of calcium from milk and yogurt. Am J Clin Nutr 1985; 42: 1197-1200. Corazza GR, Strocchi A, Sorge M, Benati G, Gasbarrini G. Prevalence
24
25
26 27
28
35
and consistency of low breath H2 excretion following lactnlose ingestion. Possible implications for the clinical use of the H2 breath test. Dig Dis Sci 1993; 38: 2010-2016. Zeitz M, Ullrich R, Riecken EO. The role of the gut-associated lymphoid tissue in the pathogenesis of the acquired immunodeficiency syndrome (HIV-infection). Proceedings of the Fifth International Congress of Mucosal Immunology. London: Kluwer Academic Publishers. 1990: 655-659. Chlebowski P~T,Grosvenor MB, Bernhard NH, Morales LS, Bulcavage LM. Nutritional status, gastrointestinal dysfunction, and survival in patients with AIDS. Am ] Gastroenterol 1989; 84: 1288-1293. Leading article. HIV-associated enteropathy. Lancet 1989; ii: 777778. Ellakany S, Whiteside TL, Schade RR et al. Analysis of intestinal lymphocyte subpopulations in patients with acquired immunodeficiency syndrome (AIDS) and AIDS-related complex. Am l Clin Pathol 1987; 87: 356-364. Ullrich R, Zeitz M, Heise W e t al. MucosaI atrophy is associated with loss of activated T cells in the duodenal mucosa of human immunodeficiency virus (HIV)-infected patients. Digestion 1990; 46(Suppl. 2): 302-307.
The Impact of HIV Infection on Lactose Absorptive Capacity G. R. Corazza, L. Ginaldi, N. Furia, G. Marani-Toro 1, D. Di Giammartino 1 and D. Quaglino Department of Internal Medicine, University of L'Aquila, Via S.Sisto 22/E, 67100 L'Aquila, Italy, and 1Division of Infectious Diseases, "Ospedale Civile", Teramo, Italy Forty HIV-infected adult patients at different disease stages and 44 healthy volunteers were evaluated for lactose malabsorption using the hydrogen breath test after 20 g lactose ingestion. All subjects were previously tested for breath hydrogen (H2) excretion after 12 g lactulose ingestion. The presence of intestinal superinfections, gastrointestinal symptoms and the intensity of clinical intolerance after lactose load were accurately searched in each patient. The cumulative H2 excretion after lactulose did not significantly differ between the different groups studied. The prevalence of lactose malabsorption turned out to be significantly higher (P<0.001) in HIV-infected patients (70%) than in controls (34%). Moreover, in patients in more advanced disease stages the degree of lactose malabsorption was significantly greater than in patients at earlier disease stages, who did not differ from healthy volunteers. Furthermore the degree of lactose intolerance was significantly greater (P<0.001) in symptomatic patients than in those without intestinal symptoms and in healthy volunteers, while no significant difference was observed between these latter groups. The results here demonstrate the negative impact of HIV infection on lactose absorptive capacity in adult patients, particularly marked in more advanced stages of the disease, suggesting that, in addition to the presence of the virus alone, other factors may contribute to determine the enterokinetic alterations responsible for lactase deficiency.
Introduction Symptoms of malabsorption may frequently occur not only in patients with advanced HIV infection but also in the early stages of the disease. ~ In these cases malabsorption is considered a secondary event to the socalled HIV-associated enteropathy, 2-5 histologically characterized by partial villous atrophy 6 and mucosal inflammation. 7 The finding that HIV has been identified by various techniques either in crypt 8 or villous enterocytes 9 supports the theory that HIV by itself, even in the absence of opportunistic diseases or secondary malignancies, may have a role in the development of this enteropathy. Because a low lactase activity has been demonstrated in HIV-infected patients, 6'9 it is possible that lactose malabsorption may be responsible for some of the intestinal symptoms. Lactose malabsorption has been reported in adult patients with various stages of HIV infection by hydrogen breath test/''9 These studies, however, are subject to criticisms because they have been carried out on a limited number of patients and because the load of 50 g of lactose represents a non-physiological dose for a great number of individuals. 1° Furthermore, in these Address correspondence to Dott. L. Ginaldi. Accepted for publication 19 November 1996.
0163-4453/97/040031 +05 $12.00/0
investigations the capacity of patients to excrete appreciable H2 amounts following lactulose ingestion was not previously tested. The purpose of this study was to evaluate prevalence and degree of malabsorption of a more physiological dose of lactose in an adequate number of adult patients in various stages of the disease, in whom the capacity to produce hydrogen had been previously tested on the basis of breath H2 excretion after lactulose ingestion.
Materials and Methods Patients Forty-two HIV seropositive patients and 45 HIV-negative healthy volunteers, matched for sex and age with the patients, were enrolled in the study. Of the patients, 29 were males and 13 females, ranging in age from 16 to 45 (median 29.9). Twenty-six subjects had a history of intravenous drug abuse, three were homosexual men, two were haemophiliacs and 11 were heterosexual. The HIV infection was diagnosed by the ELISA test and confirmed by Western blot analysis for viral antibodies in all patients. The presehce of intestinal symptoms (diarrhoea, vomiting, abdominal pain, weight loss) was accurately © 1997 The British Societyfor the Study of Infection
32
G.R. Corazza e t al,
searched in all patients. Diarrhoea was defined as more t h a n two loose bowel actions per day for 2 weeks, and weight loss as a loss of at least 10% of body weight, n A search for intestinal pathogens was systematically performed and included stool cultures by means of standard microbiological cultivation assays for Salmonella enteritidis, shigella, Yersinia enterocolitica, Campylobacter jejuni, Enterotoxigenic enterobacteria, rotavirus and adenovirus. Stools were also examined for ova and parasitic agents, including Cryptosporidium and Isospora belli. Stool cultures and smears for Mycobacterium were also performed. Patients with persistent diarrhoea and/or gastrointestinal symptoms, in which initial stool studies did not show a pathogen, underwent endoscopy with biopsy for cytomegalovirus or microsporidian infections. All patients underwent a complete clinical evaluation including a t h o r o u g h historical and physical examination. The recommendations of the Centers for Disease Control 12 were followed to define the stage of disease. An informed consent was obtained from all of the patients and controls taking part in the study.
Breath Hydrogen analysis None of the patients or controls was undergoing antibiotics or cytostatic drugs, and none of them was under the influence of drugs capable of modifying the oro-cecal transit time during the 15 days before the investigation. All subjects ate a meal of rice and meat the evening before the test 13 and then fasted for the next 12 h. Smoking and physical exercise were not permitted for 30 min before and during the test, and a m o u t h wash with 20 ml of 0.05% chlorohexidine solution preceded breath sample collection.14 Breath testing was carried out for 4 h after ingestion of test solution, is Alveolar samples were collected every 30 min using the 'two bag method'. 16 Measurement of H2 concentration was performed using a gas chromatograph dedicated to the measurement of H2 (Model 12, Ouintron, Milwaukee, WI, U.S.A.). The accuracy of the detector w a s + 2 parts per million (ppm), with a linear response range between 2 and 150 ppm. All the tests were started between 0800 and 0900 hours. Breath H2 testing after lactulose and lactose ingestion were performed with a gap of 2 days from one to the other. A dose of 12 g of lactulose (120 ml of tap water) was administered and cumulative H2 excretion was estimated by calculating the area under the curve of H2 concentration in end-expiration breath samples against time. 13 Only those patients who had breath H 2 excretion higher than l O p p m after lactulose load repeated the test with a 20 g dose of lactose (100 ml). An increase in breath H2 concentration > 2 0 p p m above
the baseline value was considered indicative of lactose malabsorption. During the 8 h after lactose ingestion, the appearance of symptoms of intolerance (meteorism, flatulence, abdominal pain, diarrhoea) was evaluated and their intensity scored according to the following criteria: absent = 0, mild = 1, moderate = 2, severe = 3. On the basis of the partial scores, a cumulative index of lactose intolerance was calculated. 17
Statistical analysis Statistical analyses of results were performed by means of non-parametric methods, including the Fisher's exact probability test, the Spearman rank correlation test and the Mann-Whitney-Wilcoxon test. Differences were considered statistically significant for P values less t h a n 0.01.
Results Of the 42 patients studied, eight were asymptomatic (ASY), nine had lymphadenopathy (LAS), 13 had AIDSrelated complex (ARC) and 12 had AIDS. Eleven of these patients (four ARC and seven AIDS) had clinical manifestations of gastrointestinal dysfunction, as evidenced by persistent diarrhoea, abdominal pain or weight loss. Microbiological evaluations showed the presence of intestinal pathogens in five of these. Cryptosporidium, Campylobactel; Mycobacterium, Cytomegalovirus and Giardia lamblia were found, respectively in four cases of AIDS and one of ARC. No identifiable enteric pathogens were found in the other symptomatic or asymptomatic patients. The aetiology of the diarrhoea or other gastrointestinal symptoms remained, therefore, undetermined in six cases. As far as H2 excretion is concerned, two patients - one with AIDS, one with ARC - and one healthy volunteer did not undergo lactose breath test because of inadequate breath Ha excretion after 12 g lactulose ingestion. Figure 1 shows that the cumulative H2 excretion after 12 g lactulose did not significantly differ between different groups studied. The proportion of lactose malabsorbers in all HIVpositive patients was 70% and significantly higher (P<0.001) than the 34% observed in healthy volunteers. All patients with evidence of intestinal superinfections had lactose malabsorption. Figure 2 shows the distribution of AH2 (ppm) values after lactose ingestion in healthy volunteers and HIVinfected patients at different disease stages. In patients with ARC and AIDS, the degree of H2 breath excretion increases gradually with progression of disease. Asymptomatic patients or those with LAS did not differ significantly
HIV Infection and Lactose Malabsorption Healthy ASY volunteers
8 000
4 000
• 1. q, 2
ARC
Healthy volunteers
AIDS 10
i!.
16 000
E
LAS
33
9 ® >
HIV patients HIV patients without with intestinal intestinal symptoms symptoms
81 7 6
• "
;
~
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000
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--
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--
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im
~
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lie
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o -
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2225Z:2:22:
o~
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2:::::::::::::
.............
L__NS '
Figure 1. H2 cumulative excretion after 12 g lactulose ingestion in healthy volunteers and HIV-infectedpatients divided according to the disease stages.
120
Healthy ASY volunteers
LAS
ARC
AIDS
o
co
•
o
110 100 90 80 70 o
E
& 60 50 <
|
40
:
30 20 I
10 0
t
&
NS
Z
•
P < 0.05 NS
- - P <
NS
P < 0.05
H
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0 . 0 1 - -
1
< 0.01
L _ _ p
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P
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~c_p < 0 . 0 0 1 ~
P < 0.001
'
Figure 3, Index of lactose i n t o l e r a n c e after ingestion of 2 0 g lactose in h e a l t h y v o l u n t e e r s a n d HIV-infected patients w i t h o u t a n d w i t h i n t e s t i n a l symptoms.
from healthy volunteers with regards to H2 excretion. In patients with AIDS, this excretion was found to be significantly higher than in the other groups. The prevalence of lactose malabsorption was of the order of 12.5% in ASY, 77.7% in LAS, 83.3% in ARC and 90.9% in AIDS. The open circles indicate the patients with intestinal symptoms who, as reported, belong to the ARC and AIDS groups and are all lactose malabsorbers. In Fig. 3, HIV-infected patients have been divided on the basis of the presence or absence of intestinal symptoms. The degree of lactose intolerance measured during the test and in the 8 h following in symptomatic patients was significantly greater than in asymptomatic patients and healthy volunteers. No significant difference was found between healthy volunteers and HIV patients without symptoms. In HIV-infected patients there was a positive correlation between hydrogen excretion after lactose ingestion and the symptom score of intolerance (r = 0.55; P<0.O01).
Discussion
- - J
< 0.001
•
•
-
-
0.001
Figure 2. DH2 excretion after 2 0 g lactose ingestion in h e a l t h y v o l u n t e e r s and HIV infected p a t i e n t s at different disease stages. ( O ) = patients with intestinal symptoms.
The technology employed in the present study for the evaluation of prevalence and degree of lactose malabsorption has also been used in investigations carried out in HIV-infected children. 18 2o There is general agreement that both prevalence and degree are higher in patients than in controls. Prevalence but not degree of lactose malabsorption has been incidentally reported in two small series of HIV adult patients, 6'9 but both these studies suffer from numerous pitfalls. In both, the number
34
G.R. Corazza et al.
of patients studied was extremely small, the results were not compared to those obtained from a control population, in both 50 g of lactose were given, a dose which is considered not physiological, 21'1°'22 and the ability of individual patients to raise breath H2 excretion after lactulose was not previously tested. 23 In contrast, in the present study an adequate n u m b e r of HW-infected patients has been investigated, and this has enabled a subdivision into subgroups and has therefore allowed the possibility of investigating the prevalence and degree of lactose malabsorption in the various stages of disease; the results were compared with those obtained from a group of healthy volunteers chosen at random from the general population; furthermore, 20 g of lactose were given, and this dose corresponds to a cupful of milk; and finally, lactose H2 breath test was preceded by lactulose Hi breath test both in patients and in healthy volunteers. This latter device was introduced to ascertain that all candidates were H2 excretors and also for the purpose of excluding major differences in cumulative H2 excretion between the study groups that could be related to differences in bacterial intestinal flora. Our results confirm that also in adults there is a negative impact of HIV infection on lactose absorptive capacity. Prevalence and degree of lactose malabsorption are in fact significantly greater in HIV-infected patients than in the general population, and, in the former, both are higher in the more advanced stages of the disease. Only patients with ARC and AIDS presented with intestinal symptoms at the time of enrolment in the study, and in both of these groups all symptomatic patients malabsorbed 20 g of lactose. Our findings are in agreement with the results of Zuin et al. 2° who demonstrated that children in more advanced disease stage had a higher prevalence of malabsorption of low lactose doses than did patients at earlier stages and non-infected children, while no statistically significant differences were observed with a higher standard dose. Moreover, the finding that in symptomatic patients disaccharide intolerance was significantly higher than in patients without symptoms appears to indicate that lactose malabsorption and intolerance m a y in some measure contribute to the development of intestinal symptoms in these patients. Numerous factors m a y be responsible for lactose malabsorption in HIV-infected patients. Both opportunistic infections (all five patients who were suffering from intestinal superinfections showed evidence of malabsorption and intolerance) as well as presence of the virus alone m a y be responsible for a slowing-down of enterocyte kinetics, and consequently a maturation defect in brush border enzymes. 4'24 The present study was not intended to establish which of these mechanisms could
be the cause of lactose malabsorption in our patients. However, its greater prevalence in the more advanced disease stages suggests that other factors, such as viral burden, the degree of malnutrition, 2~'26 the increasingly progressive mucosal T lymphocyte depletion, 27'24'28 all contribute, in addition to the presence of the virus itself, to develop those enterokinetic alterations responsible for lactase deficiency in HIV-infected patients.
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