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Flashcards in Hypoglycemia/Insulinoma Deck (19)
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1
Q

What is the definition of Hypoglycemia?

A

Plasma glucose low enough to cause signs or symptoms

Impairment of brain function

<70 mg/dl

2
Q

What is Whipple’s Triad?

A
  • Symptoms/signs consistent w/ hypoglycemia
  • Low measured plasma glucose concentration
  • Resolution of symptoms/signs w/ increasing plasma glucose
3
Q

What is the counter-regulatory hormone response to hypoglycemia?

A

know table on slide 5

4
Q

What are the signs & symptoms of hypoglycemia?

A
  • Neurogenic (autonomic)
    • Tremor
    • Palpitations
    • Anxiety/arousal
    • Sweating
    • Hunger
  • Neuroglycopenic (most concerning)
    • Cognitive impairment
    • Behavioral changes
    • Psychomotor abnormalities
    • Visual changes
    • Seizures
    • Coma
5
Q

What is the differential diagnosis for Hypoglycemia? (5)

A
  • Drugs
    • Insulin
    • Insulin secretogogue
  • Critical Illness
    • Liver, kidney, heart failure
    • Sepsis
    • Severe malnourishment
  • Hormone Deficiency
    • Cortisol
  • Endogenous Hyperinsulin
    • Insulinoma
    • Nesidioblastosis
    • Post-gastric bypass
  • Insulin Autoimmune
    • Antibody to insulin
    • Antibody to insulin receptor
6
Q

What is an Insulinoma?

Epidemiology?

Distribution?

A
  • Insulin-secreting tumors of pancreatic origin that cause hypoglycemia
  • 1-4 people per million
  • 1-2% of all pancreatic neoplasms
  • Benign, solitary, intrapancreatic, <2 cm (90%)
  • Evenly distributed throughout the pancreas
7
Q

Insulinoma diagnosis is made per ________ studies when ________.

A

Hormonal

Hypoglycemic

8
Q

Imaging helps to localize the insulinoma ______ the diagnosis is made.

A

After

9
Q

How is a supervised fast used to diagnose insulinoma?

A
  • Provoke hormonal responses that maintain Euglycemia
  • Normally symptomatic hypoglycemia should not occur after a prolonged fast given gluconeogenesis
  • Up to 72 hr fast can be used to determine the presence & etiology of hypoglycemia
10
Q

What are the end points for the supervised fast test?

A
  • Glucose < 45 mg/dl
  • Signs/symptoms of hypoglycemia
  • > 72 hrs have elapsed
  • Glucose < 55 mg/dl + Whipple’s triad
11
Q

C-peptide is a marker for ___________.

A

endogenous insulin secretion

12
Q

What are the cutoffs for patients w/ insulinomas after a 72 hr fast?

A

Glucose < 55 mg/dl

Insulin > 3 μU/ml

13
Q

What are the 6 markers used to determine the etiology of hypoglycemia after a 72 hr fast?

A
  • Insulin
  • C-peptide
  • Sulfonylurea screen
  • Pro-insulin
  • ß-hydroxybutyrate
  • Response to 1 mg IV glucagon
14
Q

Hypoglycemia

Insulin after 72 hr fast

A
  • < or > 3 μU/ml
  • Insulin-mediated will have elevated insulin concentrations
  • Increased insulin: insulinomas, sulfonylureas, insulin autoimmune, exogenous insulin
15
Q

Hypoglycemia

C-peptide after 72 hr fast

A
  • < or > 0.2 nmol/l
  • Exogenous (pharmacologic) insulin does not contain C-peptide
  • Sulfonylureas & insulinomas will increase insulin & C-peptide
16
Q

Hypoglycemia

Sulfonylureas after 72 hr fast

A

Screen blood as sulfonylureas use & insulinoma could otherwise be indistinguishable (both raise insulin & C-peptide)

17
Q

Hypoglycemia

ß-hydroxybutyrate after 72 hr fast

A
  • Insulin has anti-ketogenic effect
  • Insulinoma patients have lower levels when fasting
  • End of fast = < 2.7 mmol/l
  • Progressive rise after 18 hrs could also indicate negative fast
18
Q

Hypoglycemia

Response to IV glucagon after 72 hr fast

A
  • Insulin is anti-glycogenolytic
  • Hyperinsulinemia permits the retention of glycogen w/i the liver
  • Patients w/ insulin-mediated hypoglycemia respond to 1 mg of IV glucagon w/ a subsequent increase in plasma glucose at the end of a supervised fast
19
Q

What is the Mixed Meal Test?

When is it used?

A
  • Not standardized & validated like 72 hr fast
  • Used to evaluate patients w/ postprandial symptoms
  • Measure glucose, pro-insulin, insulin & C-peptide pre-meal (fasting) and every 30 min post-meal (mixture fats, carbs, protein)
  • Trying to confirm if hypoglycemia is an etiology of the symptoms & clarify if insulin mediated
  • Helpful in patients w/ postprandial symptoms following for example, GI procedures (Roux en Y gastric bypass surgery)