The Carcinoid Syndrome: Chronic Treatment with Para-Chlorophenylalanine

Para-chlorophenylalanine is a potent depleter of tissue serotonin (5-hydroxytryptamine). Since 5-hydroxytryptamine may contribute to the pathogenesis of several aspects of the carcinoid syndrome, for 1 year we treated a patient with this syndrome with para-chlorophenylalanine. A 59-year-old man developed chronic diarrhea, hepatomegaly, right-sided valvular heart lesion, and cutaneous flush. Exploratory abdominal examination showed ileal carcinoid tumor metastatic to liver and nodes. Urine 5-hydroxyindoleacetic acid and serum 5-hydroxytryptamine levels were abnormally high. Para-chlorophenylalanine treatment promptly reduced both levels to normal and halted the diarrhea. Chronic treatment with para-chlorophenylalanine controlled the production of 5-hydroxytryptamine and diarrhea but did not prevent tumor growth, flushing, or progression of cardiac lesions.