5-Hydroxyindoleacetic acid (5-HIAA)
A useful screening test for carcinoid syndrome1,2
Urinary 5-HIAA, the primary metabolite of serotonin, has diagnostic and prognostic value in NETs associated with carcinoid syndrome.1-3 5-HIAA is measured by high-precision liquid chromatography in a 24-hour urine sample.4
The sensitivity of 5-HIAA in NETs ranges from 5% to 50% (65%-85% in ileal NETs), and specificity can reach 100%.4 Elevations in 5-HIAA are predictive of poor outcome5 and progressive carcinoid heart disease.6
Considerations when ordering 5-HIAA testing
5-HIAA may detect NETs/metastases that secrete serotonin but may not identify other NETs.1
5-HIAA may be increased by ingestion of foods high in serotonin, such as avocados, bananas, pineapples, walnuts, and kiwifruit.2
Certain medications, including guaifenesin, acetaminophen, salicylates, and L-dopa, may also affect 5-HIAA. Patients should be instructed to avoid these foods and medications before and during urine collection.2
1. Mamikunian G, Vinik AI, O'Dorisio TM, Woltering EA, Go VLW. Diagnosing and treating gastroenteropancreatic tumors, including ICD-9 codes. In: Neuroendocrine Tumors: A Comprehensive Guide to Diagnosis and Management. 4th ed. Inglewood, CA: Inter Science Institute; 2009:1-43.
2. Jensen RT, Doherty GM. Carcinoid tumors and the carcinoid syndrome. In: DeVita VT Jr, Hellman S, Rosenberg SA, eds. Cancer: Principles & Practice of Oncology. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005:1559-1574.
1. Mamikunian G, Vinik AI, O'Dorisio TM, Woltering EA, Go VLW. Diagnosing and treating gastroenteropancreatic tumors, including ICD-9 codes. In: Neuroendocrine Tumors: A Comprehensive Guide to Diagnosis and Management. 4th ed. Inglewood, CA: Inter Science Institute; 2009:1-43.
2. Jensen RT, Doherty GM. Carcinoid tumors and the carcinoid syndrome. In: DeVita VT Jr, Hellman S, Rosenberg SA, eds. Cancer: Principles & Practice of Oncology. 7th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005:1559-1574.
3. Rorstad O. Prognostic indicators for carcinoid neuroendocrine tumors of the gastrointestinal tract. J Surg Oncol. 2005;89(3):151-160.
4. Ferolla P, Faggiano A, Mansueto G, et al. The biological characterization of neuroendocrine tumors: the role of neuroendocrine markers. J Endocrinol Invest. 2008;31(3):277-286.
5. Formica V, Wotherspoon A, Cunningham D, et al. The prognostic role of WHO classification, urinary 5-hydroxyindoleacetic acid and liver function tests in metastatic neuroendocrine carcinomas of the gastroenteropancreatic tract. Br J Cancer. 2007;96(8):1178-1182.
6. Møller JE, Connolly HM, Rubin J, Seward JB, Modesto K, Pellikka PA. Factors associated with progression of carcinoid heart disease. N Engl J Med. 2003;348(11):1005-1015.
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