Hypoglycemia/insulinoma Flashcards
in 72 hour fast, proinsulin level >5pmol/L consistent with
insulinoma
action of cortisol and growth hormone in response to hypoglycemia
limit glucose utilization and enhance glucneogensis (if hypoglycemia persists)
end points for 72 hour fast
glucose
glucose < 55 + whipples triad
signs/symptoms of hypoglycemia
>72 horus
critical timing for measurements of hypoglycemia
must be taken while patient is experiencing hypoglycemia
level for hypoglycemia if on insulin or sulfonylurea
Whipple’s triad for hypoglycemia
Symptoms/signs consistent
low plasma glucose (typically <70)
resolution of symptoms with feeding
physiologic defenses against hypoglycemia
reduction in insulin
increase glucagon
increase in epinephrine
action of epinephrine in response to hypoglycemia
increase substrate for gluconeogenesis at beta-2 adrenergic receptors
inhibit insulin secretion at Alpha 2
measurements and indications for mixed meal test
measure glucose, proinsulin, insulin, C peptide pre-meal (fasting) and every 30 minutes post meal
Used to evaluate patients with postprandial symptoms (clarify if insulin mediated)
often after Gastric Bypass
Patients with insulin mediated hypoglycemia response to IV glucagon at end of supervised fast
mechanism
increase in plasma glucose (response to insulin)
hyperinsulin secretion permits retention of glycogen whtin liver
(normal patients would have no remaining glycogen)
neuroglycopenic symptoms of hypoglycemia
cognitive impairment
behavior changes
psychomotor abnormalities
visual changes
seizures
coma
lab value cut offs to distinguish patients with insulinomas from normal in 72 hour fast
glucose 3microU/ml
action of glucagon in response to hypoglycemia
increased glycogenolysis and gluconeogenesis at liver
order of hormonal response to hypoglycemia
- decrease insulin
- increase glucagon
- increase epinephrine
- Cortisol and growth hormone
neurogenic (autonomic) symptoms of hypoglycemia
tremor
palpitations
anxiety/arousal
sweating
hunger
