| Specimen requirement | 24 Hr urine U2 bottle (* Do not discard the acid preservatives inside the bottle!) |
| Authorisation code required | No |
| 24 Hr available service | No |
| Precaution | Guideline for Specimen CollectionIdeally, the collection should be made when the patient is symptomatic. During the collection of the 24 Hr urine specimen, the patient’s diet should not include bananas, plums, tomatoes and walnuts, all of which contain large amounts of 5-HT. Preferably, the patient should not be taking any drug therapy during the collection; if the patient is receiving drugs, the form of treatment should have been established for at least two weeks prior to the collection. Smoking should be avoided during the collection as the nicotine in tobacco may release 5-HT from body stores. See list of Interfering Food and Drugs. |
| Method | Liquid chromatography-tandem mass spectrometry |
| Reference interval |
< 42.6 µmol/day (Source: modified from manufacturer’s kit insert) |
| Clinical indication | Detection of carcinoid tumours |
| Result interpretation |
Increased 24 Hr excretion of HIAA is found in carcinoid tumours particularly if metastasis to the liver, or beyond, has occurred. Urinary excretion may be normal if the tumour is confined to the portal circulation. |
| Measurement of uncertainty | See table. |
| Frequency of measurement | Biweekly |