SEROTONIN, CATECHOLAMINES, HISTAMINE, AND THEIR METABOLITES IN URINE,PLATELETS, AND TUMOR-TISSUE OF PATIENTS WITH CARCINOID-TUMORS

We monitored long-term (median 11 months) concentrations of platelet s erotonin and urinary serotonin, 5-hydroxyindoleacetic acid, and seven catecholamine metabolites in 44 patients with carcinoid tumors. Tumor serotonin and catecholamine contents (11 patients) and urinary histami ne and N-methylhistamine (15 patients) were determined. Consistently i ncreased concentrations of indoles, notably platelet serotonin, were o bserved in 96%, 43%, and 0% of patients with mid-, fore-, and hindgut carcinoids, respectively. Urinary dopamine metabolites, notably 3-meth oxytyramine, were consistently increased in 38%, 20%, and 7% of patien ts with mid-, hind-, and foregut carcinoids, respectively. For urinary norepinephrine/epinephrine metabolites, notably normetanephrine and m etanephrine, these data were 33%, 20%, and 14%, respectively. Midgut c arcinoid tumors had the highest serotonin contents, whereas concentrat ions of catecholamines were independent of primary localization. There was no consistent relation between biogenic amine contents in tumors and urinary excretion of the amine metabolites. Occurrence of carcinoi d syndrome was related to increased serotonin production rate. Increas ed histamine production is not an important feature in patients with l ung carcinoids or liver-metastasized ileum carcinoids.