5-HIAA
| Category | Biochemistry >> Metabolic |
|---|---|
| Test background |
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 can be characterised by symptoms of flushing and diarrhoea. Abdominal pain, bronchial asthma, heart failure and pellagra may also be present. However, it is usually only associated with the mid gut tumours that have metastasized to the liver and are found predominantly in the ileum and appendix. |
| Clinical Indications |
Carcinoid syndrome, characterised by symptoms of flushing and diarrhoea. Abdominal pain, bronchial asthma, heart failure and pellagra may also be present. |
| Reference range | <40 μmol/24 h |
| Sample & container required | 24 hour urine collection acidified |
| Sample volume | 24 hour urine collection |
| Transport storage | Stable at 2-8°C however freezing pending dispatch recommended. Sample can be sent by first class post. |
| Turnaround time | 2 weeks |
| Notes | Certain foodstuffs may cause false positive results. These include: aubergines, avocados, bananas, caffeine, pineapples, plums, tomatoes, walnuts, and medications such as cough mixtures containing guaifenesin/glycerol guaiacolate. The patient must follow the specified diet for 72hrs with the urine being collected in the last 24hrs (patient diet sheet for 5HIAA collection is provided together with the acidified container). Requesting clinicians should ensure relevant medications from the diet sheet are removed or submitted as clinical details at receipt. Samples with pH>6.0 are unsuitable for this assay. |