Endocrine report 11/20: Insulinoma work-up and Hypoglycemia

Thanks to our endocrinology attending for sharing his expertise this morning! Interesting case of a patient undergoing an insulinoma work-up.

Take-home points: when evaluating hypoglycemia, remember to first think about if it’s real. Questions to consider: (1) Are symptoms present when hypoglycemia is present (remember Whipple’s Triad…)? (2) Does the finger stick correlate with the serum glucose (pseudohypoglyemia)?


Additional teaching points

  • There is such a thing as pseudohypoglycemia which occurs when there is impaired microcirculation (even cold hands!) which causes low capillary glucose levels, but the serum blood glucose is totally normal.
  • When screening family history for MEN syndromes, often people do not know about their relatives detailed history. However you can ask about kidney stones as a way to get at hyperparathyroidism causing hypercalcemia as part of MEN1 and MEN2A.
  • Whipple’s triad refresher:
  1. Symptoms of hypoglycemia
  2. Low blood glucose at the time of symptoms
  3. Resolution of symptoms when glucose is normalized
  • Framework for hypoglycemia
    • Insulin mediated
      • Endogenous: insulinoma, autoimmune disease (Ab to insulin or insulin receptor), post-prandial syndrome
      • Exogenous: accidental, surreptitious (insulin administration, sulfonylurea)
    • Non-insulin mediated: alcohol, sepsis, hepatic failure, hormone deficiency (e.g. adrenal insufficiency), malnutrition, artifact
  • Insulinoma work-up:
    • Fasting for 72 hours (observed)
    • By 24hours, 75% of patients with insulinoma will declare themselves with hypoglycemia, and 96% by 48hrs!
    • When hypoglycemia occurs, check labs at the same time: insulin level (high), C-peptide (high), proinsulin (high), sulfonylurea screen, ketones (low), glucose (low)


Evernote: http://www.evernote.com/l/APgRbWrS4t9AbbZP0GGW6br_ROTgwZ_knpk/


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