The brain controls the production of serotonin, which is an important hormone produced in the body. It helps in the transmission of nerve impulses and also affects the moods of a person. It constricts the blood vessels and is involved in the sleep-wake cycle. The serotonin hormone breaks down in the liver and produces metabolites, such as 5-hydroxyindoleacetic acid – ; 5-HIAA, which is excreted in the urine. The 5-HIAA urine test is used to measure 5-HIAA levels in the urine, thus giving an estimate of the amount of serotonin being produced in the body.
Why is the test performed?
A 5-HIAA (5-hydroxyindoleacetic acid) test may be ordered to help diagnose and monitor carcinoid tumours.
When is the test ordered?
The test may be ordered if an individual shows the signs and symptoms indicative of a carcinoid tumour. Such symptoms include:
- Appearance of a deep red colour on the face and neck
- Increased heart rate
- Breathing difficulties.
The test may also be ordered for monitoring the progress of treatment in people undergoing treatment for a carcinoid tumour.
How is the sample collected?
A urine sample is collected in a big sterile container over a period of 24 hours.
How to prepare for the test?
It is better to inform the doctor about all the medicines and supplements that the patient is taking, as they may affect the test result. Some fruits like kiwi, avocados, tomatoes, bananas, pineapples, plums and walnuts may also affect the test results and should be avoided for at least 3 days prior to taking the test.