Flashcards in Hypoglycemia Deck (44)
Is hypoglycemia a diagnosis?
No it's a sign. You need to correct the glucose, then determine and correct the underlying problem.
Which organ is most dependent on glucose?
About how long does liver glycogen last in an average fasting adult?
3 sources of glucose?
4 hormones acting directly on effector organs during fasting?
Which processes for fasting adaptation does glucagon increase?
Which processes for fasting adaptation does epinephrine increase?
Which process for fasting adaptation does cortisol increase?
Which process for fasting adaptation does growth hormone increase?
Blood glucose cutoffs for...
Activation of counterregulatory processes?
Symptoms of hypoglycemia?
Counter-regulation at 65-70mg/dL.
Symptoms at 50-55 mg/dL.
Cognitive dysfunction at 45-50 mg/dL.
Diagnostic and therapeutic thresholds for hypoglycemia?
< 50 mg/dL is diagnostic.
< 70 mg/dL merits therapy. (I think that's what the slide says)
What 3 things compose Whipple's Triad for hypoglycemia? Why is it important to satisfy them?
Symptoms of hypoglycemia.
Measured low blood glucose at time of symptoms.
Correction of symptoms with food/glucose.
Important to satisfy these because the symptoms of hypoglycemia are non-specific.
What are neurogenic vs. neuroglycopenic symptoms of hypoglycemia?
Neurogenic: Autonomic (cholinergic and adrenergic) responses to low glucose -palpitations, sweating, hunger, tremor, etc.
Neuroglycopenic: Brain stops working - headache, blurry vision, focal deficients, seizure, etc.
What's one reason why people can progress to neuroglycopenic symptoms without much warning?
Frequent hypoglycemia can blunt the autonomic responses to hypoglycemia - so there's less warning.
This is called Hypoglycemia-associated Autonomic Failure (HAAF).
Why must you rapidly process blood samples collected for glucose levels?
RBCs in there will use it up.
2 clinical types of hypoglycemia?
Fasting hypoglycemia: 12-72hrs without food.
Post-prandial hypoglycemia. (uncommon)
4 causes of post-prandial hypoglycemia?
Early Dumping Syndrome - in gastric bypass surgery, way food hits gut can cause insulin overreaction.
Early diabetes - dysregulated insulin.
Congenital metabolic disorders - eg. fructose intolerance.
3 types of fasting hypoglycemia?
Failure of counter-regulation.
Defect in glucose/ketone production.
What's the most common cause of hyperinsulinemic hypoglycemia in adults? In children?
Adults: Insulinoma. (I'm surprised it's not overdose on insulin... maybe that's not included)
Children: Congenital hyperinsulinism.
What happens if you give glucagon in hyperinsulinemic hypoglycemia? How does this contrast with other hypoglycemias?
Blood glucose will rise, because liver glycogen is not depleted.
In other hypoglycemias, glycogen is depleted.
Review: What do you measure to determine endogenous insulin production?
If you have too much insulin, what's the big picture effect on various energy sources in the blood?
There's no evidence of trying to compensate for low blood sugar:
Glucose low, fatty acids low, ketones low.
Proinsulin levels when there's an insulinoma?
Treatment for insulinoma?
What's the most common and severe mutation causing congenital hyperinsulinism? What is the function of this gene/protein normally? Responsiveness to drugs?
Loss of function mutations in the ATP-inhibited (that's my term...) K+ channel of beta calls (SUR or Kir6.2 are the real terms).
Normally, when beta cells are trying to make insulin, ATP is increased, which inhibits this K+ channel, leading to insulin secretion.
This mutation is not diazoxide-responsive.
What are the 2 most important drugs used in congenital hyperinsulinism? How do they work?
(there's a 3rd one mentioned as well...)
Diazoxide: Keeps the ATP-inhibited K+ channel of beta cells open.
Somatostatin (analogues): Inhibit Ca++ influx that causes secretory vesicle release.
-Octreotide: Activates ATP-inhibited K+ channel, acts on Ca++ signaling (has more/worse side effects).
What do GLUD1 mutations do? Why does that matter?
Treatment for it?
Mutations in GLUD1 impair the ability of GTP to inhibit glutamate dehydrogenase (GDH).
Overactive GDH makes too much ATP in beta cells -> inhibition of ATP-inhibited K+ channel -> hyperinsulinemia. (also causes hyperammonemia)
Treatment = diazoxide to keep the K+ channel open.
2 different forms of immune-mediated hypoglycemia?
Agonist antibodies to insulin receptor.
Anti-insulin antibodies, which can sequester insulin and then release it suddenly in boluses.
What are the take-home points about hypoglycemia caused by cortisol and growth hormone deficiencies?
It's more mild, manifests as ketosis during fasting, can be seen by other symptoms/signs of the deficiency, treated with hormone-replacement.