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Investigations and Scans

Those accessing the service may undergo a range of tests and scans to investigate or monitor the disease.

Blood tests

We may ask you to have blood tests, sometimes on a regular basis to monitor your disease. Some can be done at your local hospital or GP surgery but some may need to be undertaken at a major hospital as they need to arrive at the lab quickly. We will advise you which option you need to take.

24-hour urine collection

Urinary 5-HIAA (5-hydroxyindoleacetic acid)

  • 5-HIAA is a waste product of the breakdown of serotonin which is excreted from the body in urine. We measure this as an indirect way of measuring how much serotonin is in the body. Serotonin can be released by neuroendocrine tumour cells, especially in those with carcinoid syndrome. 
  • When completing the 24 hour urine collection, there are instructions to follow to ensure an accurate measurement, such as avoiding certain foods. These instructions can vary between health boards so please check the Health Board instructions when you obtain the collection bottle.
  • The 5-HIAA collection instructions for Cardiff and Vale Health Board can be found here
  • 24 hour collection is completed by passing your first urine of the day into the toilet as normal, this is your start time, then every urine passed after this until the same time the next morning is collected into the bottle.

Having a Scan

The main way we investigate or monitor your disease is by CT and MRI scans. These are generally requested in a hospital local to you.

CT scan

you may be asked to have a blood test in the lead up to your scan. This tells how well your kidneys are working and are you able to tolerate the contrast dye. You may be given a drink to have before the scan to improve the quality of the scan. You may also need an injection a special dye to also help with this.

MRI scan

This is a magnetic scan that gives detailed images of the body. It helps us assess your disease and plan any treatment. The scanner can be noisy and you may be given ear plugs to wear. The radiologist will talk to you through an intercom. In certain situations, patients cannot have an MRI scan, this is usually if you have any metal in your body such as a pacemaker, please let us know.

Gallium PET

Some patients will be recommended a Gallium68 PET scan for us to be able to map your disease. This is a specialised whole-body scan that is available in several in the UK. Currently this scan is not available in Wales and patients are referred to London for this. If you are referred for a Gallium68 PET, please contact the NET CNSs for further details. A similar scan available in South Wales is an ‘Octreotide’ scan which could be used as an alternative. Not all patients with NETs require these scans.


For some types of NETs (stomach, duodenal, rectal), you may need an upper or lower gastrointestinal endoscopy (OGD, colonoscopy or flexible sigmoidoscopy) as a one-off procedure or on a regular basis. This may occur in a hospital close to you or in University Hospital of Wales or University Hospital Llandough.

View information about endoscopy

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