Insulin Secreting Tumours Flashcards
What’s the metastatic rate of canine insulinoma?
45-64%
How is insulin released from the pancreatic beta cells?
glucose enters the Beta cells –> metabolizes ATP –> closes the K+ channels –> decrease K+ efflux –> depolarizes –> opens Ca2+ channel –> insulin exocytosis
What are the four counter-regulatory hormones for hypoglycemia?
- glucagon*
- catecholamines*
- GH
- glucocorticoids
* most important short term response
What are some signs associated with neuroglycopenia?
- seizure
- collapse/ weakness
- ataxia, disorientation
- mental dullness
- visual disturbances
What are some signs associated with catecholamine release?
- tremors
- nervousness
- hunger
Is peripheral neuropathy possible with insulinoma?
yes, has been reported. likely a paraneoplastic syndrome
What are some differentials for hypoglycemia?
- excessive insulin secretion
- insulinoma
- hepatic tumour
- beta cell hyperplasia - decrease glucose production
- liver disease
- glycogen storage issues
- hypoadrenocorticism
- hypopituitary - excessive glucose use
- sepsis
- extreme exercise - drug related
- insulin
- propranolol
- oral hypoglycemics (ex. sulfonylurea)
- etc. - Spurious
- antidepressants
What imaging modality has a better chance of detecting pancreatic tumours?
CT
though optimal imaging in people has not been identified
What’s the acute treatment for hypoglycemia?
dextrose infusion.
- can try dexamethasone and/or somatostatin analogue
- glucagon
need to make sure that there is enough glucose as it will increase insulin secretion as well
What’s the long-term treatment for insulinoma?
Surgery!
What are some common medical therapeutic options for insulinoma?
- Prednisone
- increases gluconeogenesis and gluose-6-phosphate activity, while decreasing tissue glucose uptake and stimulating glucagon secretion - Diazoxide
- inhibits the closure of the K+ pump, so no depolarization, no insulin exocytosis
- well tolerated - Octreotide
- somatostatin analogue
- inhibits insulin secretion
- but also inhibits GH and glucagon
What’s the utility of streptozocin?
chemo that directly targets the pancreatic beta cells & metastatic lesions
- nephrotoxic – prolonged fluid diuresis required (7h)
- MST 4-6m
- recommendation still requires further study
What’s the prognosis for insulinoma?
prolonged survival possible with surgery
