Bowel dysfunction in cystic fibrosis: importance of breath testing

J Paediatr Child Health. 1998 Feb;34(1):79-82. doi: 10.1046/j.1440-1754.1998.00159.x.


Objective: To investigate the prevalence of carbohydrate malabsorption and bacterial overgrowth in children with cystic fibrosis (CF) and abnormal stool pattern referred for breath hydrogen testing.

Methods: Results from 89 tests using lactose, sucrose and lactulose in 54 children with CF were compared with 5430 tests on children with non-CF-related stool abnormalities.

Results: Children with CF were more frequently unable to ferment lactulose to hydrogen (39% vs. 20%, P<0.03); they had significantly longer oro-caecal transit times (mean 99 vs. 68 min, P<0.0003); they had a higher incidence of bacterial overgrowth (32% vs. 7%, P<0.003) and sucrose malabsorption (47% vs. 14.5%, P<0.004); but they had no increase in lactose malabsorption (40% vs. 31%). Children with bacterial overgrowth in both groups had longer transit times (CF 123 min, non-CF 108 min) compared to the non-CF children without overgrowth (68 min) and reference normal children (69 min).

Conclusions: Bacterial overgrowth and carbohydrate malabsorption, particularly of sucrose, should be considered when assessing children with CF and abnormal stool patterns.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Breath Tests*
  • Carbohydrate Metabolism*
  • Child
  • Child, Preschool
  • Cystic Fibrosis / complications*
  • Digestive System / microbiology
  • Gastrointestinal Transit
  • Humans
  • Hydrogen / metabolism
  • Infant
  • Intestinal Diseases / complications*
  • Intestinal Diseases / etiology
  • Lactose / metabolism
  • Malabsorption Syndromes / complications*
  • Malabsorption Syndromes / diagnosis
  • Sucrose / metabolism


  • Sucrose
  • Hydrogen
  • Lactose