Carcinoid tumors can produce excessive amounts of biogenic amines, notably serotonin. We assessed psychiatric symptoms in carcinoid patients and peripheral metabolism of tryptophan, the precursor of serotonin.
Twenty consecutive patients with carcinoid syndrome underwent a structured psychiatric interview applying DSM-IV (Diagnostical Statistical Manual) criteria. Tumor activity was measured by determination of 24-hour urine excretion of 5-hydroxyindoleacetic acid (5-HIAA) and platelet serotonin levels. Plasma tryptophan levels were measured and compared with sex- and age-matched references.
Fifteen patients (75%) fulfilled diagnostic DSM-IV criteria for a disorder of impulse control. Tryptophan plasma levels were lower in patients compared with controls (p = .031) and were correlated negatively with urinary 5-HIAA excretion (p = .001).
Impulse control disorders are prevalent in patients with carcinoid syndrome. The serotonin production by the tumor possibly decreases the tryptophan pool in the cerebrospinal fluid, which is the essential substrate for the production of brain serotonin as a pivotal neurotransmitter.
From the Departments of Biological Psychiatry (S.R., J.C.B., J.S.d.B., J.K.), Laboratory Medicine (I.P.K.), and Medical Oncology (P.H.B.W., E.G.E.d.V), University Hospital Groningen, the Netherlands.
Address correspondence and reprint requests to Elisabeth G.E. de Vries, MD, PhD, Department of Medical Oncology, Hanzeplein 1, P.O. Box 30.001, 9700 RB Groningen, The Netherlands. E-mail: firstname.lastname@example.org
Received for publication September 17, 2003; revision received January 12, 2004.