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

Specimen Type Describes the specimen type needed for testing


Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.

Container/Tube: Plastic, 10-mL urine tube (Supply 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.

3. Patients should not eat 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, all of which are high in serotonin, for 48 hours before and during collection.

4. Patients should avoid taking the following medications for 48 hours before and during collection as they can falsely raise or lower 5-HIAA levels and interfere with results.

-Pain relievers (specifically those containing acetaminophen [Tylenol], salicylates [aspirin] or phenacetin)

-Cough syrups containing guaifenesin or antihistamines

-Nasal drops and sprays

-Muscle relaxants containing mephenesin or methocarbamol (Robaxin, Flexeril, and Valium for example)

-Antidepressants including tricyclic antidepressants (imipramine, for example) and monamine oxidase inhibitors (MAOIs) (Nardil, for example)

-Hypertensive medications (Reserpine, for example)

-Isoniazid (antibiotic used to fight tuberculosis and other diseases)

-Methenamine (antibiotic used to fight urinary tract infections)

-Heparin (anticoagulant used as a blood thinner)

-L-dopa (Levodopa such as Sinemet, or Methyldopa, used to treat high blood pressure, for example)

-Phenothiazines (Compazine or Thorazine for example, used to treat mental or emotional disorders)

5. Patient should also avoid tobacco, tea and coffee for 48 hours before and during specimen collection.

Additional Information:

1. 24-hour volume is required.

2. See Urine Preservatives in Special Instructions for multiple collections.

Forms: If not ordering electronically, complete, print, and send an Oncology Test Request Form (T729) with the specimen



Urine Preservative Collection Options







6N HCl

Yes (30 mL)

50% Acetic Acid



Yes (5 g)


Yes (30 mL)


Yes (15 mL)

Boric Acid

Yes (10 g)


Yes (10%)

Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.

1 mL

Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected









Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.

Specimen TypeTemperatureTime
UrineRefrigerated (preferred)56 days
 Frozen 365 days