URINARY FREE CORTISOL EXCRETION IN PATIENTS WITH HYPERSEROTONINEMIA FROM THE CARCINOID-SYNDROME

To determine if patients with chronic hyperserotoninemia from the carcinoid syndrome have increased basal adrenocortical function, the urinary free cortisol excretion of 17 patients with carcinoid tumors and the carcinoid syndrome, 12 patients with carcinoid tumors without the carcinoid syndrome and 17 normal subjects was determined. There was no significant difference in the urinary free cortisol excretion of the patients with carcinoid tumors and the carcinoid syndrome (133 .+-. 20.0 nmol/24 h), patients with carcinoid tumors without the carcinoid syndrome (115 .+-. 29 nmol/24 h) and the normal subjects (96 .+-. 9 nmol/24 h). There was no correlation between the urinary free cortisol secretion and urinary 5-hydroxyindoleacetic acid or serum serotonin concentration in the patients with the carcinoid syndrome. There was a suggestion that patients with 5-hydroxytryptophan (5-HTP) secreting carcinoid tumors had higher urinary free cortisol excretion than patients with predominantly serotonin (5-HT) secreting carcinoid tumors. This may be due to the fact that the non-polar 5-HTP molecule penetrates the blood-brain barrier more effectively than the polar 5-HT molecule. 5-HTP is then converted to 5-HT within the brain. None of the 29 patients with carcinoid tumors had clinical or laboratory evidence of the ectopic ACTH syndrome.