Abnormalities of fasting serum concentrations of peptide YY in the idiopathic inflammatory bowel diseases.

Peptide YY has been localized within human ileocolonic endocrine cells and may contribute to the regulation of gastric secretion and gastric emptying in man. Since our previous studies had shown decreased colonic concentrations of peptide YY in the idiopathic inflammatory bowel diseases, a specific radioimmunoassay was used to measure fasting serum concentrations of peptide YY in healthy controls and in patients with adenocarcinoma of the rectum, idiopathic chronic active liver disease and hepatic cirrhosis, ulcerative colitis, and Crohn's disease. In healthy controls and in patients with adenocarcinoma of the rectum, serum concentrations of peptide YY ranged from 50 to 260 pg/ml. Serum concentrations of peptide YY in patients with hepatic cirrhosis ranged from 59 to 717 pg/ml. Serum concentrations of peptide YY in patients with ulcerative colitis were similar to healthy controls. In patients with Crohn's disease, serum concentrations of peptide YY were less than 50 pg/ml in three patients who had had a previous proctocolectomy, and were more than 260 pg/ml in 14 patients who had had previous resection of more than 48 cm of ileum or presently had symptomatic Crohn's disease subsequently requiring surgical resection of a total of more than 75 cm of ileum. These results suggest that most circulating peptide YY is released from the colorectal region. Hepatic cirrhosis, previous ileal resection, and symptomatic Crohn's disease were associated with elevation of fasting serum peptide YY. The mechanism of increased fasting serum peptide YY in patients with Crohn's disease could be the loss of an ileal inhibitory factor or possibly an increased release of colonic peptide YY in response to fat malabsorption. The effect of alteration of serum peptide YY concentrations on the pathophysiology of Crohn's disease is yet unknown.