Visceral hypersensitivity and intolerance symptoms in.pdf

Visceral hypersensitivity and intolerance symptoms in lactose malabsorption M. DI STEFANO, E. MICELI, S. MAZZOCCHI, P. TANA, F. MORONI G. R. CORAZZA Department of Medicine, IRCCS S.Matteo Hospital, University of Pavia, Pavia, Italy Abstract Lactose malabsorption is not always associ- ated with intolerance symptoms. The factors respon- sible 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 dur- ing 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 13C-octanoic and lactulose breath tests. Lactulose administration induced a sig- nificant 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 sig- nificantly correlated with the reduction of discomfort thresholds. Visceral hypersensitivity should be con- sidered in the induction of intolerance symptoms in subjects with lactose malabsorption. Keywords barostat, diagnosis, lactose intolerance, lactose malabsorption, visceral sensitivity. INTRODUCTION Lactose malabsorption is a widespread condition throughout the world caused by a genetically deter-