Enteroglucagon and peptide Y-Y response after construction of a pelvic reservoir in humans. The results of an investigation of plasma levels of gastrointestinal hormones in patients after the construction of a pelvic reservoir are reported. Enteroglucagon (EG) and peptide tyrosine-tyrosine (PYY), two hormones believed to play a relevant role in the adaptive response to bowel resection, were investigated using a specific radioimmunoassay in basal conditions and after a standard meal. Pouch patients showed a statistically significant increase in basal levels of both enteroglucagon and PYY compared with control subjects (P less than 0.02 and P less than 0.001, respectively). The response of enteroglucagon to food ingestion, evaluated by means of the total integrated response, was similar in patients and controls. Conversely, the response of PYY was significantly increased in pouch patients compared with control cases (P less than 0.02). Results of this investigation suggest that gut hormones may be involved in mediating the adaptive response of the intestine to pouch construction. Changes of gut peptides may explain, at least in part, the functional results observed after pouch construction. 