Hydroxyindoleacetic Acid (5-HIAA), Urine

Diagnostic Use

5-Hydroxyindoleacetic acid (5-HIAA) is the major metabolite of serotonin and is excreted in the urine. Elevated levels of urinary 5-HIAA are seen in many patients with neuroendocrine tumours causing carcinoid syndrome.

Carcinoid syndrome is characterised by the triad of diarrhoea, flushing and bronchospasm and occurs when neuroendocrine tumours (NETs) metastasise to a site outside of the portal circulation (usually the liver). Carcinoid syndrome is usually associated with midgut NETs.

Department

Specialist Biochemistry

Delphic Registration Code

HIAA

Laboratory Handling

Separating

Enter volume and duration of urine collected.

Test Adds

Refrigerated (preferred) 56 days, frozen 365 days

Synonyms

5-HIAA
5HIAA
HIAA (Urine)

Turnaround Time

14 days

Test Code

3477

Specimen Type

• 24hr Urine

Specimen Requirements

Tube/Container Type:

Preferred

• 24hr Urine Container

Acceptable

• Pottle
• BD Urine Tube (no additive)

Minimum Sample Volume (ml)

2

Pre-testing Requirements

False positive results are possible if foods high in serotonin are consumed during or immediately before the testing period. Please see the link below for further instructions on how to prepare for this test.

Urinary 5-HIAA patient instructions

Additional Specimen Information

Timed 24 hour urine collection, either acidified or un-acidified.

Aliquot Instructions

Sample Type

• Urine

Transport to Lab

Ambient (8 - 24 degrees Celsius)
If overnight - Chilled (2 - 8 degrees Celsius)

Interpretation

An elevated urinary 5-HIAA result has a sensitivity of approximately 70% for carcinoid syndrome.  Test performance can be improved by ensuring that there is no dietary consumption of serotonin or related metabolites in the 48 hours leading up to and during the collection period.  As a rule, the higher the result is above the upper reference limit, the higher the probability of carcinoid syndrome.

Carcinoid syndrome is most commonly associated with midgut NETs.  Foregut and hindgut NETs may not secrete serotonin, in which case 5-HIAA may not be elevated.  These tumours may secrete other amines, including serotonin precursors which can be converted to serotonin in the liver.  Other NET biomarkers including chromogranin A, serotonin and histamine may be of use in the investigation of these cases.

Reference Intervals

<50μmol/24hrs

Test Method

LC-MSMS

Non-Funded Test Cost

$107.58 (Exclusive of GST)

Billing Code

3479

Contact Information

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Contact Information

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