Recurrent abdominal pain in children and the endogenous opiates: a brief hypothesis.

The aetiology of recurrent abdominal pain in children (RAP) remains unclear. Some features of this syndrome suggest that an opiate-like mechanism may be involved. The evidence for this is reviewed, and it is hypothesised that RAP may result from a differential gastrointestinal response to stress mediated by the endogenous opiate system.