Urine tests for neuroendocrine tumours (NETs)

Some NETs increase the amount of serotonin in the body. Serotonin is a chemical the body makes that sends messages between different parts of the brain. It helps control lots of functions, such as how you sleep, your mood, and your appetite. The liver changes serotonin into a chemical called 5HIAA. The body then passes 5HIAA out through the urine.

You will be asked to save all the urine you pass in a 24-hour period. Your doctor will then test it for 5HIAA.

Certain foods, drinks and medicines can raise your levels of 5HIAA. You may need to avoid these for a few days before and during the urine collection.

Blood tests for neuroendocrine tumours (NETs)

If you have a NET, the levels of some chemicals in the blood may rise. This is mainly serotonin and a protein called chromogranin A (CgA). You will need to have blood samples taken to check the levels of these chemicals.

You will also have a blood test to count the number of healthy blood cells in your blood. This is called a full blood count or FBC. Another blood test will check how well your kidneys and liver are working.

About our information

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    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Professor Tim Iveson, Consultant Medical Oncologist.

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