Hydroxyindole Acetic Acid (5-HIAA - plasma)
5-hydroxyindoleacetic acid (5HIAA) is a metabolite of serotonin. Measurement of 5HIAA in plasma is used to exclude serotonin-secreting neuroendocrine carcinoid tumours as a cause of current symptoms. Features of carcinoid disease or the carcinoid syndrome include flushing, diarrhoea, wheezing and heart disease. Plasma 5HIAA concentration increases when renal function is impaired in the absence of a carcinoid tumour. Plasma creatinine is measured when 5HIAA is above the reference range to aid interpretation.
|Availability||Weekdays. Assay is run fortnightly.|
|Additional Information||Carcinoid disease is characterised by tumours of the argentaffin cells which produce excessive amounts of serotonin. The serotonin is usually rapidly metabolised by the liver to 5-hydroxyindoleacetic acid which is excreted via the kidneys. However in mid gut tumours with liver metastases, or in foregut tumours where the serotonin drains directly into the systemic circulation, the serotonin can cause flushing, diarrhoea, wheezing and heart disease - the so called 'carcinoid syndrome'.|
|Turn Around||20 days|
|Send to||First Class Post to: Specialist Laboratory Medicine
|Collection Con||"Overnight fast - avoid serotonin containing foods day before blood collection i.e. bananas, walnuts, pineapples, tomatoes, plums, avocado. Collect into Heparin Tube (WITHOUT GEL).
For referral labs: if sample is not sent within 48hrs of collection freeze
|Sample REQ||Centrifuge and separate ideally within 4 hours of collection. Store at 4C or freeze prior to sending. Avoid multiple freeze-thaw cycles. Minium volume 1mL plasma.|