Carcinoid tumors are tumors that secrete excessive amounts of the hormone serotonin . Serotonin is converted by the body to 5-HIAA . The precursor to serotonin is tryptophan , an amino acid that is also used by the body to manufacture niacin and certain proteins . In children, carcinoid usually occurs in the appendix and removal of the appendix results in a complete cure. Signs of pellagra develop when most of the available tryptophan is used by the tumor to produce serotonin , which then prevents the body from manufacturing niacin .
Total protein is often low.
Serotonin levels are elevated. Treatment Surgery is usually not indicated except for isolated tumor . The goal of treatment is to control the symptoms. Increased protein in diet is often recommended and nicotinamide supplements may be prescribed. Somatostatin and similar medications may be effective in reducing the episodes of flushing and diarrhea and in reversing the hypotension .