Further tests

Octreotide scan (OctreoScan) - This is a useful diagnostic test for many neuroendocrine tumours that have special somatostatin receptors in their surfaces. Octreotide binds with these receptors, and when it is combined with a mildly radioactive ingredient and then injected via a vein in the arm it can help reveal the site of tumours under a special scan. The tumours appear 'lit up' on the screen.

However, only 50% of insulinoma patients have these receptors on their tumours so an octreotide scan may not be appropriate. But there are still other diagnostic options available.

CT or MRI scan - Both computerised tomography (CT) or magnetic resonance imaging (MRI) of the pancreas can determine the position and size of an insulinoma and regular scans can be useful to find out its rate of growth.

Endoscopic ultrasound - A diagnostic procedure that is similar to gastroscopy can help find even small insulinomas in the pancreas. A tumour just 1cm in size can be picked up this way.

PVS sampling - There are other interventional tests that can be done if there is still doubt. A procedure that involves testing blood taken from the portal vein (that carries blood from the GI tract to the liver) following an injection of calcium (that stimulates insulin secretion) can reveal insulinomas smaller than 1cm. This test is called PVS (portal vein sampling) and is done under sedation.

Once the diagnosis of insulinoma has been made, it is likely you will be screened for the presence of MEN 1 (Multiple Endocrine Neoplasia, type 1) syndrome, a condition that includes tumours of parathyroid glands, pancreatic neuroendocrine tumours and pituitary tumours.

What does screening for MEN1 involve?

A blood test to estimate levels of calcium and certain hormones in the blood.