Patients should abstain, if possible, from foods, medications, over-the-counter drugs, and herbal remedies for at least 72 hours prior to the test. 24-hour collections are generally recommended, but random collections may also be used. Refrigeration is the most important aspect of specimen preservation. Foods and medications that are associated with altered Urinary HIAA results: Decreased Results: Aspirin, Chlorpromazine(Thorazine), Corticotropin, Dihydroxyphenylacetic, Ethanol, Gentisic acid, Homogentisic acid, Hydrazine derivatives, Imipramine(Tofranil), Isocarboxazid(Marplan), Keto acids, Levodopa, Mao inhibitors, Methenamine, Methyldopa (Aldochlor), Phenothiazines(Compazine), Perchlorperazine, Promazine, Promethazine. Increased Results : Acetaminophen, Acetanilid, Caffeine, Coumaric acid, Ephedrine, Fluoracil, Glycerol Guaiacolate (Guaifenesin), Melphalin (Alkeran), Mephenesin, Methamphetamine (Desoxyn), Methylcarbamol, Naproxen, Nicotine, Phenacetin, Phenmetrazine, Phenobarb, Pentolamine, Raulwolfia, Reserpine, Robaxin, Valium (Diazepam) Foods: Avocados, Bananas, Egg plant, Plums, Pineapple, Tomatoes and Walnuts