Neurology: Case of the Month

Test Yourself — Patient 53

Hypoglycemic Encephalopathy; Insulinoma

  1. Symptoms of hypoglycemia, in non-diabetic patients, are always preceded by hunger and symptoms of adrenergic activation.
    • [ A ] True
    • [ B ] False
  2. During the oral glucose tolerance test (GTT), normal volunteers can occasionally have decreases in their plasma glucose level below 30 mg/dl (1.6 mmol/L). Blood glucose levels below 50 mg/dL (2.8 mmol/l) will develop in about 10% of normal subjects, and as many as 25% will have values below 60 mg/dl (3.3 mmol/L).
    • [ A ] True
    • [ B ] False
  3. Jamaican vomiting sickness and epidemics of fatal encephalopathy in preschool children in Burkina Faso have been related to consumption of unripe ackee fruit. The natural toxin, hypoglycin A, and its major metabolite, methylenecyclopropylacetic acid, are potent hypoglycemic agents. The mechanism underlying the hypoglycemic action of these compounds is:
    • [ A ] Increase in insulin secretion
    • [ B ] Decrease in the rate of Beta-oxidation of fatty acids
  4. Which of the following statements regarding medications and hypoglycemia is FALSE?
    • [ A ] Glucagon is effective in correcting alcohol-related hypoglycemia.
    • [ B ] The highest incidence of hypoglycemia is associated with the longest-acting and most potent sulfonylurea drugs (glyburide > chlorpropamide > glipizide; glimepiride > meglitinide).
    • [ C ] Pentamidine can induce Beta-cell membrane dysfunction, causing insulin leakage and subsequent hypoglycemia.
    • [ D ] Beta-adrenergic blocking agents may decrease awareness of hypoglycemia.
  5. Which of the following statements about insulinomas is TRUE?
    • [ A ] C-peptide levels in blood are typically suppressed in the presence of insulinoma.
    • [ B ] Absence of fasting hypoglycemia virtually excludes a diagnosis of insulinoma.
    • [ C ] Insulinomas are typically large tumors, coming to clinical attention as often from their local mass effects as from symptoms due to insulin oversecretion.
    • [ D ] The clinical effects of insulinoma may be mimicked by islet cell hyperplasia or nesidioblastosis.

 

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