VIPomas and the watery diarrhoea syndrome.

Vaso-active intestinal polypeptide (VIP) is a recently discovered polypeptide widely distributed throughout the gastro-intestinal tract and nervous system. Elevated plasma VIP levels are found in gut and neural endocrine tumours producing the watery diarrhoea syndrome. Fifty per cent of these tumours are intrinsically malignant and the mortality rate may be as high as 30% even from the bening growths owing to the serious metabolic sequelae of the syndrome. The plasma VIP level is not elevated in any other non-tumourous diarrhoeal condition. The biological action of VIP closely resembles the clinical features of the Verner-Morrison syndrome and experimental evidence strongly suggests that VIP is the causal agent. The measurement of plasma VIP is of exceptional diagnostic value, since detection of elevated levels enables early removal of the tumour and may be life-saving.