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Test ID: HIAA 5-Hydroxyindoleacetic Acid (5-HIAA), 24 Hour, Urine

Reporting Name

5-Hydroxyindoleacetic Acid, U

Useful For

Biochemical diagnosis and monitoring of intestinal carcinoid syndrome

Specimen Type


Necessary Information

24-hour volume is required.

Specimen Required

Patient Preparation:

1. Some medications (see below) could interfere with test results. The ordering provider should decide if any medications should be stopped and when they should be restarted.

2. For 48 hours before patients start their urine collection and during the 24 hours they collect urine:

Limit the following to 1 serving per day:




-Caffeinated beverages or foods


If clinically feasible, discontinue the following medications at least 48 hours before specimen collection:

-Acetaminophen (Tylenol or generic versions)



-Cough syrups

-Cold and flu medications

Supplies: Urine Tubes, 10 mL (T068)

Container/Tube: Plastic, 10-mL urine tube (T068)

Specimen Volume: 5 mL

Collection 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.

Additional Information: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens in Special Instructions for multiple collections.

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Urine Refrigerated (preferred) 56 days
  Frozen  365 days

Reference Values

≤8 mg/24 hours


For SI unit Reference Values, see

Day(s) and Time(s) Performed

Monday through Thursday; 11 a.m.

Friday; 2 p.m.

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
HIAA 5-Hydroxyindoleacetic Acid, U 1695-6


Result ID Test Result Name Result LOINC Value
9248 5-Hydroxyindoleacetic Acid, U 1695-6
TM35 Collection Duration 13362-9
VL33 Urine Volume 3167-4

Clinical Information

5-Hydroxyindoleacetic acid (5-HIAA) is the major metabolite of serotonin and is excreted in the urine. Intestinal carcinoid tumors along with neuroendocrine tumors can produce excess amounts of 5-HIAA and serotonin especially in individuals with carcinoid syndrome. Carcinoid syndrome is characterized by carcinoid tumors, flushing, heart disease, and hepatomegaly.


Measurement of 5-HIAA in a 24-hour urine specimen can diagnose carcinoid disease with a high specificity.


Elevated excretion of 5-hydroxyindoleacetic acid is a probable indicator of the presence of a serotonin-producing tumor, if pharmacological and dietary artifacts have been ruled out.

Clinical Reference

1. de Herder W: Biochemistry of neuroendocrine tumours. Best Pract Res Clin Endocrinol Metab 2007 Mar;21(1):33-41

2. Manini P, Andreoli R, Cavazzini S, et al: Liquid chromatography-electrospray tandem mass spectrometry of acidic monoamine metabolites. J Chromatogr B Biomed Sci Appl 2000 July 21;744(2):423-431

3. Mashige F, Matsushima Y, Kanazawa H, et al: Acidic catecholamine metabolites and 5-hydroxyindoleacetic acid in urine: the influence of diet. Ann Clin Biochem 1996;33:43-49

4. Vinik A, Feliberti E, Perry RR: Carcinoid Tumors. In: Endotext. Edited by LJ De Groot, P Beck-Peccoz, G Chrousos. South Dartmouth, MA, Inc; 2000. Available at

5. Serotonin syndrome. In POISINDEX System. Edited by RK Klasco, CR Gelman, LT Hill. Greenwood Village, Colorado, Micromedex, 2002

Analytic Time

2 days (not reported on Saturday or Sunday)

Method Name

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Urine Preservative Collection Options

Note: The addition of preservative or application of temperature controls must occur within 4 hours of completion of the collection.







6N HCl

Yes (30 mL)

50% Acetic Acid

Preferred (25 mL)


Yes (5 g)


Yes (30 mL)


Yes (15 mL)

Boric Acid

Yes (10 g)

Thymol (10% in isopropanol)

Yes (10 mL)




Mayo Clinic Laboratories | Genetics and Pharmacogenomics Catalog Additional Information: