Effect of Oral 5-HTP Intake on Urinary 5-HIAA Excretion

5-HTP is a common over the counter product that is sold in natural food stores and via the Internet. It is claimed to improve sleep problems, depression, anxiety, compulsive disorders, restless leg syndrome, migraines, fibromyalgia, and low pain threshold.Increased levels of 5-HIAA in the urine can be a of a specific type of cancer, called carcinoid tumor. Urinary 5-HIAA levels can also be increased by a number of food products and drugs. Oral 5-HTP is not known as a cause of elevation of 5-HIAA in urine. However, recent information suggests that 5-HTP may cause an increase. In this study we examine the effect of oral 5-HTP intake (100 mg at bedtime for 10 days) on 5-HIAA excretion in the urine, following a prospective, double-blind placebo-controlled study design. Understanding this effect may help to determine which tests should be done in a patient with increased 5-HIAA excretion who's also taking 5-HTP.