Biochemistry question from kaplan

[anbuitachi]

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I'm not clear about one of the biochem explanations, if someone can help me clear it up please

question says:
Underweight 4 yr old - semicomatose at 10am.
Plasma glucose, urea, glutamine low.
Acetoacetate elevated
Lactate normal.
Increase in blood glucose was achieved by controlled infusion of glucagon or alanine.
Which metabolic pathway is most likely deficient?

The answer says normal lactate, and hyperketonemia, eliminates answer choices - glycogenolysis, gluconeogenesis, and lipolysis.

I think i get the lipolysis cause of the ketones. But how is glycogenolysis and gluconeogenesis ruled out? I'm not understanding the connection. What is wrong w/ normal lactate?

Thanks

 

[Little Soldier]

im guessing infusion of glucagon could rule out glycogenolysis and gluconeogenesis. gluconeogenesis might also be ruled out by infusion of alanine. sorry i cant be much help, MSI here

 

[Jonari]

I'm not clear about one of the biochem explanations, if someone can help me clear it up please

question says:
Underweight 4 yr old - semicomatose at 10am.
Plasma glucose, urea, glutamine low.
Acetoacetate elevated
Lactate normal.
Increase in blood glucose was achieved by controlled infusion of glucagon or alanine.
Which metabolic pathway is most likely deficient?

The answer says normal lactate, and hyperketonemia, eliminates answer choices - glycogenolysis, gluconeogenesis, and lipolysis.

I think i get the lipolysis cause of the ketones. But how is glycogenolysis and gluconeogenesis ruled out? I'm not understanding the connection. What is wrong w/ normal lactate?

Thanks

im guessing infusion of glucagon could rule out glycogenolysis and gluconeogenesis. gluconeogenesis might also be ruled out by infusion of alanine. sorry i cant be much help, MSI here

Nice.

In add'n if gluconeogenesis wasn't working say due to pyruvate carboxylase deficiency, pyruvate will get shunted into lactate production via LDH. This will reduce the NADH to NAD, so that it can be reused again. Hence, lactate would be elevated, but in this case it's not - so would rule out ggenesis.

 

[Donald Juan]

im guessing infusion of glucagon could rule out glycogenolysis and gluconeogenesis. gluconeogenesis might also be ruled out by infusion of alanine. sorry i cant be much help, MSI here

I agree. Infusion of glucagon and alanine wouldn't restore glucose levels if there was a defect in glycogenolysis or gluconeogenesis