Endocrine cells are present throughout the gut as part of the diffuse neuroendocrine system. Formerly known as the amine precursor uptake and decarboxylation (APUD) system. Gut hormone tumours arise from these cells / APUDomas.

Tumour Biology

Derived from pluripotent stem cells. Tumours may be:

• Non-functioning
• Functioning - secrete a wide range of hormones .7% secrete more than one hormone.

Non-Functioning Tumours

• Can reach a large size in an apparently well patient
• Often mistakenly identified as adenocarcinoma
• Produce non-functionally active peptides e.g pancreatic polypeptide and neurotensin
• Stain with - neurone specific enolase and chromagranin

Functioning Tumours

Usually present with symptoms of hormone excess:

• insulin
• gastrin
• glucagon
• serotonin
• somatostatin
• vasoactive intestinal polypeptide (VIP)

Diagnosis

• Fasting plasma sample
• Raised hormone levels
• Other causes of raised levels excluded

Causes of raised Gut Hormones

• All Hormones Non-fasting Chronic renal failure
  
• Insulin Sulphonylurea treatment
  
• Gastrin Hypercalcaemia, Achlorhydria, PPI/H2 antagonist
  
• Glucagon Hepatic failure, OCP Prolonged fast/stress