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5-Hydroxyindoleacetic acid

About This Test

Department: Biochemistry


  • 24-hour urine (acidified container)


Turnaround Time:

2 weeks

The Clinical Biochemistry Laboratory has changed the method used for measurement of urine 5HIAA. From 17/06/19 urine 5HIAA analysis will be performed using an in-house tandem mass spectrometry method. Results using the new method will be accompanied by a new normal range and an appropriate interpretative comment.


Investigation and monitoring of carcinoid syndrome.

Please supply full clinical details supporting referral of samples for analysis.

Instructions for collection of 24-hour urine samples

Certain foods should be avoided 72 hours prior to collection and during collection: bananas, coffee, avocado, tomatoes, aubergine, plums, pineapples, kiwi, walnuts and pecan nuts. Please advise patients accordingly.

5HIAA concentration may be increased by cough syrup and reserpine.

5HIAA concentration may be decreased by heparin, isoniazid, levodopa, MAO inhibitors, methyldopa. phenothiazines and tricyclic antidepressants.

Consider discontinuation of medication for 72 hours prior to collection. If this is not possible, then medication in use should be stated on the request card.

Normal range: <42 μmol/24h

Other Comments:

For more information, please see the following: 5HIAA - Lab Tests Online