Preferred Sample Type

5 Hydroxy Indole Acetic Acid (5HIAA)

Suitable Specimen Types

24 Hour Urine (Acid Collection)

5 Hydroxy Indole Acetic Acid (5HIAA)

Specimen Volume

24hr urine collection (3 mL urine required for assay)

Specimen Transport

Not applicable

Turnaround Time

7 Days

Sample Processing In Laboratory

No special transport conditions apply

General Information

Measurement of urinary 5-hydroxy indole-3-acetic acid (5HIAA) output is used in the diagnosis and follow up of patients with carcinoid tumours. These tumours are found principally in the gastrointestinal tract, but may also occur in the respiratory and urogenital tracts. The "carcinoid syndrome" is attributable to carcinoid tumours of the mid-gut with liver metastases or primary tumours, such as ovarian carcinoids, with direct drainage into the circulation. The classical syndrome consists of attacks of skin flushing, diarrhoea and less frequently bronchoconstriction. Features of the disease, which may vary between patients, are thought to be mediated by a variety of tumour-produced secretory products including the monoamine 5 hydroxytryptamine (5HT). The 5HT produced is metabolised to 5HIAA and excreted in the urine.


From 6th of April 2021 samples will be analysed at the Heartlands Laboratory

Patient Preparation

Patients should avoid serotonin-rich foods immediately prior to and during the urine collection (e.g. Banana, pineapple, tomatoes, kiwi fruit and various nuts). Please provide list of medications with request


None Given

Reference Range

5HIAA:  5-45 μmol/24h

5HIAA is affected by diet; levels can increase following ingestion of pineapples, kiwi fruit bananas and some nuts.


  • EQA Status: UKNEQAS for Urinary Catecholamines Scheme
  • EQAS Scheme: Yes

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