5HIAA urine

Keywords: 5 indole acetic acid, 5-hydroxyindole acetate

Specimen:

24 h urine collection with HCl as preservative; patient must be on a diet free of fruit and nuts for three days prior to and during collection.

Exclusion of some drugs may be required - consult pathologist.

Method:

HPLC. Spectrophotometric and fluorescence assays are not reliable.

Reference Interval:

< 50 µmol/24h

Application:

Detection of carcinoid tumours.

Interpretation:

Increased 24 h 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.

More recently, measurement of serotonin in platelets has been advocated and may be the most sensitive indole marker for the detection of carcinoid tumours.

Some drugs and foods may interfere with some methods - consult pathologist.

Reference:

Kema IP et al. J Chromatogr B Biomed Sci Appl 2000; 747: 33-48.