Evaluation of Liquid Gastric Emptying and Plasma Ghrelin in Children With Functional Dyspepsia

Functional Dyspepsia (FD) is defined as the presence of persistent or recurrent pain or discomfort centered in the upper abdomen with no evidence of organic disease likely to explain the symptoms.

This pain or discomfort must not be exclusively relieved by defecation or associated with the onset of a change in stool frequency or stool form.

Initially, the FD classification criteria included 3 subtypes: ulcer-like, in which pain is the predominant symptom; dysmotility-like, in which discomfort is the predominant symptom; and, unspecified. In 2006, however, the criteria were revised by the Rome III committees. In adults, the previous FD subtypes were eliminated and replaced by two new subtypes: (i) postprandial distress syndrome (PDS), characterized by postprandial fullness or early satiety; and, (ii) epigastric pain syndrome (EPS), characterized by epigastric pain or burning unrelated to meals. In children, the Rome II subtypes were eliminated completely. Although the Rome III subtypes have only been applied within adult criteria, there also appear to be meaningful associations in children with FD which may support their adoption in later revisions of the criteria. Specifically, both inflammation (reflected by mast cell density) and self reported anxiety and depression appear to be uniquely associated with PDS in children.

FD is a common disorder of the upper gastrointestinal (GI) tract, occurring in 26% to 34% of the general population. FD is present in as many as 80% of children being evaluated for chronic abdominal pain. FD is best explained by a biopsychological model with dysfunction within the brain-gut axis. The model suggests that FD is as a result of interaction between biological (e.g., inflammation, mechanical, or sensory dysfunction), psychological (e.g., anxiety, depression, somatization), and social (e.g., interactions with parents, teachers, or peers) factors, which may be interactive with each other. Delayed gastric emptying is one of the mechanical factors which have been implicated. Other mechanisms are visceral hypersensitivity and impaired gastric fundic accommodation.

Delayed gastric emptying has been shown in up to 66% of children with FD. Most of previous studies in children used solid GE as a measure to explain the function of pyloric emptying. However, liquids GE is a good measure to predict the function of fundic accommodation, visceral hypersensitivity as well as pyloric emptying, in which, all these mechanisms were suggested in the mechanical pathophysiological model of FD specifically PDS subtypes. In order to measure gastric emptying (GE), the 13C-acetate breath test (ABT) has the potential to replace 99mtechnetium colloid-based scintigraphy which is the "gold standard" for measuring GE. ABT has an advantage over scintigraphy in that it is a rapid, technically simple, safe and inexpensive means to assess liquid GE in children. As such, it may be more easily utilized as a diagnostic technique in standard clinical practice.