5-HIAA is a metabolite of the 5-hydroxytryptamine (5-HT) neurotransmitter (also known as serotonin). Increased 5HT turnover is characteristic of carcinoid syndrome. Tumours may occur anywhere in the GI tract and can typically secrete 5 HT, catecholamines, prostaglandins and histamine.
Carcinoid syndrome, characterised by symptoms of flushing and diarrhoea. Abdominal pain, bronchial asthma, heart failure and pellagra may also be present.
|<40 μmol/24 h|
24 hour urine collection acidified
24 hour urine collection
Certain foodstuffs may cause false positive results. These include: avocados, bananas, plums, walnuts, pineapples, tomatoes, aubergines and cough mixtures containing glycerol guaiacolate. In the event of a positive result, we would suggest the patient be asked to avoid these foodstuffs for at least 3 days before collecting a repeat sample.