Abnormal circulating hormone concentration Elevated circulating vasoactive intestinal peptide concentration 2024-03-17T14:37:46Z VIP is a gut peptide hormone originally reported as a vasodilator in 1970, has multiple physiological and pathological effects on development, growth, and the control of neuronal, epithelial, and endocrine cell functions that in turn regulate ion secretion, nutrient absorption, gut motility, glycemic control, carcinogenesis, immune responses, and circadian rhythms. The concentration of vasoactive intestinal peptide (VIP) in the blood circulation is above the upper limit of normal.