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Old 05-26-2014
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Default Diabetes biochemistry

A 10-year-old boy is brought to the emergency department because of vomiting for 6 hours. He has had excessive
thirst and excretion of large amounts of urine for 3 weeks. His pulse is 120/min, and respirations are 32/min.
Physical examination shows sunken eyes and diminished skin turgor. Serum studies show hyperglycemia, ketosis,
and metabolic acidosis. Urine studies show glucose and ketones. Which of the following sets of hepatic findings is
most likely in this patient?
Phosphoprotein
Protein Kinase A Phosphatase cAMP
(A) ↑ ↑ ↓
(B) ↑ ↓ ↑
(C) ↑ ↓ ↓
(D) ↓ ↑ ↑
(E) ↓ ↓ ↑
(F) ↓ ↓ ↓
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Old 05-26-2014
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This is from USMLE sample q.
The ans is B.
This pt has type 1 DM. I understand phosphatase should decrease.
Why PKA and cAMP are increased? Is this because of epinephrine's effect?
In type 1 DM, the glucagon should decrease (? I am not sure). Glucagon activates PKA-cAMP. So even there is more epinephrine, the PKA-cAMP may still be normal.
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Old 05-27-2014
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Quote:
Originally Posted by usmle778 View Post
This is from USMLE sample q.
The ans is B.
This pt has type 1 DM. I understand phosphatase should decrease.
Why PKA and cAMP are increased? Is this because of epinephrine's effect?
In type 1 DM, the glucagon should decrease (? I am not sure). Glucagon activates PKA-cAMP. So even there is more epinephrine, the PKA-cAMP may still be normal.
The Glucagon response in hypoglycemia is absent in Diabetics.

Insulin has no effect in Diabetics: Insulin dephosphorylates Proteins to activate them -> Phosphoprotein PHOSPHATASE is low

Epinephrin will be increased in severe hypoglycemia: Epinephrin -> Adenyly Cyclase -> ATP to cAMP -> Proteinkinase A

cAMP and Proteinkinase A go hand in hand in the same direction: increase


Don't overthink questions: I sometimes still see myself in overthinking, they might be phrased weird but all the want is to see a simple concept.
Don't answer this question by thinking: "Oh and what would be the effect of Glucagon..and if he is under severe stress Cortisol will also increase etc. etc.

Again, don't think too hard!

all the best
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The above post was thanked by:
ANUBHAV (05-27-2014), coliris (05-27-2014), usmle778 (05-27-2014)



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