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5-Hydroxyindoleacetic acid (5-HIAA) is the main metabolite of serotonin in the human body. In chemical analysis of urine samples, 5-HIAA is used to determine the body's levels of serotonin.
Additional recommended knowledge
5-HIAA, Quantitative, 24-Hour Urine; Serotonin Metabolite, 24-Hour Urine
Test for 5-HIAA
24-hour urine volume is measured and recorded on the request form.
Specimen: Urine (24-hour)
Volume: 30 mL aliquot
Minimum Volume: 1 mL aliquot
Container: Plastic urine container, no preservative (Note: 30 mL 6N HCl or 1 g/L boric acid may be added as a preservative for other tests without harm to 5-HIAA.)
Collection: The patient is instructed to void at 8 AM and discard the specimen. Then collect all urine including the final specimen voided at the end of the 24-hour collection period (ie, 8 AM the next morning). Screw the lid on securely. Label container with patient's name, date, and time. Measure and record total urine volume. Mix well; send aliquot.
Storage Instructions: Refrigerate at 2°C to 8°C up to 1 month.
Patient Preparation: Avoid bananas, avocados, plums, eggplant, tomatoes, plantain, pineapples, walnuts, and interfering drugs (see Interfering Substances Appendix) for a 72-hour period prior to and during the collection.
Reference Interval: 0.0-8.0 mg/24 hours
If a borderline elevation of 5-HIAA is found, sample should be recollected following withdrawal of dietary and medication sources that might elevate 5-HIAA (see Patient Preparation). Nontropical sprue may cause a slight increase in urinary 5-HIAA. 5-HIAA levels are lowered by renal insufficiency and after small bowel resection. When a patient strongly suspected for carcinoid syndrome shows normal or borderline increases of 5-HIAA, two possibilities should be considered: one, that large amounts of serotonin produced are not being metabolized, in which case blood levels of serotonin are required to document the diagnosis; and two, that secretion of 5-HIAA by the tumor is intermittent, in which case repeat timed specimen collections are needed to demonstrate the abnormality.
Canonman9 (talk) 17:47, 5 January 2008 (UTC)== Use ==
A serotonin analysis is most frequently performed for the diagnosis of carcinoid tumors of the enterochromaffin (Kultschitzsky) cells of the small intestine. These tumor cells release large amounts of serotonin, which can produce the clinical syndrome of flushing, diarrhea, and right-sided heart failure. The most frequently used diagnostic test for carcinoid tumors is 5-HIAA, the final metabolite of serotonin. Diagnose carcinoid tumors and syndrome; values >25 mg/24 hours (higher if the patient has malabsorption) are strong evidence for carcinoid.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "5-Hydroxyindoleacetic_acid". A list of authors is available in Wikipedia.|