False-Positive Urinary Test for 5-Hydroxyindoleacetic Acid Due to Methocarbamol and Mephenesin Carbamate

Abstract

THE urinary excretion product of serotonin, 5-hydroxyindoleacetic acid, is excreted in excess in the malignant-carcinoid syndrome.¹ The qualitative urinary test described by Sjoerdsma, Weissbach and Udenfriend² is widely used for the determination of this substance. The present report concerns the effects of the ingestion of muscle relaxants on the color reaction obtained in this test.Our experience with the following patient led to the present study.Case ReportL.B., a 25-year-old single man, entered the Albany Veterans Administration Hospital on December 1, 1958, because of nervousness. The history was that of an agitated state of several months' duration during which . . .