5 Hydroxy Indole Acetic Acid (5HIAA)

General Information

Measurement of urinary 5-hydroxy indole-3-acetic acid (5HIAA) output is used in the diagnosis and follow up of patients with carcinoid tumours. These tumours are found principally in the gastrointestinal tract, but may also occur in the respiratory and urogenital tracts. The "carcinoid syndrome" is attributable to carcinoid tumours of the mid-gut with liver metastases or primary tumours, such as ovarian carcinoids, with direct drainage into the circulation. The classical syndrome consists of attacks of skin flushing, diarrhoea and less frequently bronchoconstriction. Features of the disease, which may vary between patients, are thought to be mediated by a variety of tumour-produced secretory products including the monoamine 5 hydroxytryptamine (5HT). The 5HT produced is metabolised to 5HIAA and excreted in the urine.