Prevalence of lactose intolerance in patients with diarrhea-predominant irritable bowel syndrome: Data from a tertiary center in southern China

Background: symptoms associated with lactose intolerance (li) and diarrhea-predominant irritable bowel syndrome (ibs-d) are almost the same. these disease entities are difficult to differentiate clinically. in practice,differential diagnosis depends on self-reported patient milk intolerance. however,there is limited data on the prevalence of li in china. the aim of this study was to investigate the prevalence of li in ibs-d patients and asymptomatic healthy controls. methods: lactose malabsorption (lm) was diagnosed by a lactose hydrogen breath test (hbt) and was defined by peak breath h2 excretion over the baseline level of ≥ 20 ppm. li-related symptoms were monitored for 8 h following lactose administration. li was defined in lm patients with positive symptoms during the observation time. patients with ibs-d were additionally asked if they were intolerant to milk. results: a total of 109 eligible ibs-d patients (rome iii criteria) and 50 healthy controls were enrolled in this study. except for hydrogen non-producers,the prevalence of lm did not differ between ibs-d patients and the control group (85%,82/96 vs 72%,34/47; p = 0.061). there was,however,a higher li prevalence in ibs patients than in healthy subjects (45%,43/96 vs 17%,8/47; p = 0.002). sensitivity,specificity,and positive and negative predictive values of self-reported milk intolerance for detecting li were 58,58,53,and 63%,respectively. conclusions: prevalence of li is significantly higher in ibs-d patients than in healthy subjects. self-reported milk intolerance is a poor diagnostic predictor of li. © 2017 the author(s).