*Intake of food with a high content of serotonin (avocados, dates, eggplant, all fruit [including bananas, cantaloupe, grapefruit, kiwifruit, melons, pineapple, plantains, plums], all nuts [including hickory nuts, butternuts, pecans, walnuts], and tomatoes and tomato products) within 48 hours of the urine collection could result in falsely elevated 5-hydroxyindoleacetic acid (5-HIAA) excretion.
Numerous drugs affect the excretion of 5-HIAA by different mechanisms, including increased serotonin synthesis, metabolism, and release and inhibition of uptake. The following medications can interfere with 5-HIAA results. If clinically feasible, discontinue the following medications at least 48 hours before specimen collection. -Acetaminophen (Tylenol or generic versions) -Aspirin -Antihistamines -Cough syrups -Cold and flu medications
Patient should also avoid caffeinated beverages such as tea and coffee or caffeinated foods for 48 hours before and during the 24 hour specimen collection.
Collection Procession Instructions: 1. Collect a 24-hour urine specimen. 2. Add 25 mL of 50% acetic acid as preservative at start of collection. Use 15 mL of 50% acetic acid for children <5 years old. Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens