Urine 5-hydroxyindole acetic acid: Methodology change

Tuesday, 10 April, 2018

Why test for 5-hydroxyindoleacetic acid?
The urine 5-hydroxyindoleacetic acid (5HIAA) test is used to aid in the diagnosis of carcinoid tumours of the gastro urinary (GI) tract.
5-HIAA is the metabolite of serotonin (5-hydroxytryptamine). Serotonin is produced by the argentaffin cells of the GI tract where it is used to regulate intestinal movement. In the carcinoid tumours of the GI tract, serotonin is over-produced, thus 5-HIAA is invariably increased in classical carcinoid tumours, although some tumours may be non-secretory. 5-HIAA is also increased with high dietary serotonin intake or other GI tract disease e.g. coeliac disease.

Methodology change
Viapath’s Reference Biochemistry Department at King’s College Hospital is moving from a kit based HPLC method with electrochemical detection to a fully validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. This is primarily a service improvement, as the mass spectrometry methodology provides greater sensitivity for the quantitative measurement of 5HIAA in urine.
Reference ranges will remain unchanged (< 42 umol/24h or <4.0 umol/mmol creatine) and results generated using LC-MS/MS will be indicated on the report issued. 

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