Catecholamine metabolism in the carcinoid syndrome

Abstract

The purpose of this study was to determine if the excretion of catecholamines and their metabolites is altered in patients with the carcinoid syndrome. We found no correlation between the urinary excretion of 5-hydroxyindoleacetic acid and the excretion of 3-methoxy-4-hydroxymandelic acid, homovanillic acid or norepinephrine. There was a positive correlation between the urinary excretion of 5-hydroxyindoleacetic acid and epinephrine. An earlier report of decreased excretion of 3-methoxy-4-hydroxymandelic acid in the carcinoid syndrome can be attributed to 5-hydroxyindoleacetic acid interfering with the analytical method used for the measurement of 3-methoxy-4-hydroxymandelic acid. Patients with elevated excretion of catecholamines and their metabolites (pheochromocytoma and neuroblastoma) have normal levels of urinary 5-hydroxyindoleacetic acid. The methods used for the measurement of catecholamine metabolites in patients with the carcinoid syndrome, should not be affected by the elevated levels of urinary 5-hydroxyindoleacetic acid found in this condition.