Some children with functional abdominal pain or irritable bowel syndrome (FAP/IBS) have evidence of low-grade intestinal inflammation and/or mild alterations in the barrier function of their gastrointestinal tracts, the results of a new study indicate.

“The significance is that previously it was thought that children with these conditions had no abnormalities in their gastrointestinal tracts,” Dr. Robert J. Shulman from Texas Children’s Hospital and Baylor College of Medicine, Houston, told Reuters Health.

While studies in adults with IBS have shown increased gastrointestinal permeability and inflammation, the data in children with IBS are limited, Shulman and colleagues note in the Journal of Pediatrics.

To investigate, they measured GI permeability and levels of calprotectin, a marker of intestinal inflammation, in 93 well-characterized children with FAP/IBS and in 52 healthy children without GI complaints. All of the study subjects were between 7 and 10 years old.

Permeability was assessed on the basis of sugars recovered in urine after a standard oral dose of sucrose, lactulose, mannitol and sucralose. The researchers report that GI permeability was greater in children with FAP/IBS compared with control children in the proximal tract and in the colon.

The team also found higher fecal calprotectin concentrations in the children with FAP/IBS compared with control children, which was also statistically significant. “To our surprise, only fecal calprotectin concentration was related to pain symptoms, and in that case, only to how much the pain interfered with activity,” Shulman and colleagues note in their report. There was no correlation between GI permeability and pain-related symptoms.

“These data suggest that the relationship between GI permeability, mucosal inflammation, and pain symptoms is more complex than initially thought,” they add.

“These observations,” Shulman told Reuters Health, “are leading us to carry out studies to learn what might be responsible.” Some areas include the effects of gastrointestinal infections, food intolerances, genetic alterations, and bacterial influences. “There likely are other factors as well.”

In a related editorial, Drs. Nader N. Youssef and Maria E. Perez, from the Center for Pediatric Irritable Bowel and Motility Disorders at Goryeb Children’s Hospital at Atlantic Health, Morristown, New Jersey, point out that until recently, FAP, IBS, and other functional GI disorders were believed to be “psychosocial disorders with physical symptoms.”

The current findings, they say, serve as “further evidence that these disorders are in reality ‘physical disorders’ with organic disease and with associated local inflammation that may yet be completely understood.”

SOURCE: Journal of Pediatrics, November 2008.