Carcinoid syndrome

A rare condition caused by an intestinal or lung tumour, called a carcinoid, which secretes excess amounts of the hormone serotonin. Carcinoid syndrome is characterized by bouts of facial flushing, diarrhoea, and wheezing, but symptoms usually occur only if the tumour has spread to the liver or has arisen in a lung. Sometimes tumours in the intestine, lung, and, more rarely, the liver are removed surgically, but, in most cases, surgery is unlikely to be of benefit. In these circustances, symptoms may be relieved by drugs that block the action of serotonin.