5-hydroxyindole acetate (HIAA) - urine

24 hour 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.

<50 µmol/24 hours.

Increased 24 hour 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, measurements 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.