Pathology Handbook



Urinary 5HIAA, 5-Hydroxyindoleacetic acid

Clinical Indications

Diagnosis and monitoring of carcinoid tumours. Some tumours may not secrete 5-HIAA and levels of 5-hydroxytryptophan and 5-hydroxytryptamine may need to be measured.

Serum chromogranin levels are probably better than 5HIAA for monitoring disease

Request Form

Request on ICE


On request

Specific Criteria

Drug therapy must be stated on form

The following drugs should be avoided if possible:

  • atenolol

  • fluorouracil

  • melphalan

  • naproxen

  • oxprenalol

  • pindolol

  • paracetamol

  • guaiacolate (found in 'over-the-counter' cough remedies)

The following foods should be avoided during urine collection:

  • avacados

  • bananas

  • tomatoes

  • plums

  • walnuts

  • pineapple

  • aubergines

Turnaround Time



24 hour urine collection into acid preservative


Acidified 24 hour urine container


All drugs should be recorded on request form.

Causes for Rejection

Inadequately labelled sample

Reference Range

Less than 50 µmol/24 hours.

In patients with carcinoid, levels are typically in the range 130-1300 µmol/24hr.