why avoid fructose, galactose in Von Gierke?

[MudPhud20XX]

FA says to avoid fructose and galactose in Von Gierke. Is avoiding fructose and galactose for fructosuria and galactosemia??? Why Von Gierke? Many thanks in advance.

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[Jabbed]

Phosphate depletion.

 

[Phloston]

FA says to avoid fructose and galactose in Von Gierke. Is avoiding fructose and galactose for fructosuria and galactosemia??? Why Von Gierke? Many thanks in advance.

Fructose and galactose shunt to intermediates of glycolysis.

Fructose --> F-1-P --> DAP + GA; then the latter is phosphorylated --> DAP + G3P

Galactose --> Galactose-1-phosphate --> Glucose-1-phosphate --> Glucose-6-phosphate

These are essentially 'substrates' on the left side of the G6Pase equation and have nowhere else to go but forward, much of which will get sent to lactic acid via pyruvate.

And as the above poster has said, if they ask you why there's liver dysfunction/hepatomegaly/jaundice, it's due to phosphate depletion. Increasing the number of glycolytic intermediates requires phosphates to be put on those molecules, rather than elsewhere (e.g., glucose --> G6P), so the liver 'struggles' to compensate.

 

[wjs010]

Fructose and galactose shunt to intermediates of glycolysis.

Fructose --> F-1-P --> DAP + GA; then the latter is phosphorylated --> DAP + G3P

Galactose --> Galactose-1-phosphate --> Glucose-1-phosphate --> Glucose-6-phosphate

These are essentially 'substrates' on the left side of the G6Pase equation and have nowhere else to go but forward, much of which will get sent to lactic acid via pyruvate.

And as the above poster has said, if they ask you why there's liver dysfunction/hepatomegaly/jaundice, it's due to phosphate depletion. Increasing the number of glycolytic intermediates requires phosphates to be put on those molecules, rather than elsewhere (e.g., glucose --> G6P), so the liver 'struggles' to compensate.

Can you please elaborate on that last part? Sorry I'm on break and too lazy to look up in first aid. Lol

 

[Phloston]

Can you please elaborate on that last part? Sorry I'm on break and too lazy to look up in first aid. Lol

From "Google": Aldolase B is the major aldolase isozyme in the liver and functions in both fructose metabolism, using fructose 1-phosphate as a substrate, and in gluconeogenesis, producing fructose 1,6-bisphosphate from the two triose phosphates, glyceraldehyde-3-phosphate and dihydroxyacetone phosphate. In the absence of appreciable aldolase B activity, as in HFI patients, fructose challenge results in a rapid accumulation of fructose 1-phosphate in the liver, causing sequestration of inorganic phosphate. This drop in the intracellular phosphate pool activates AMP deaminase, leading to degradation of adenine nucleotides (13). The concomitant hypoglycemia is brought on by competitive inhibition of phosphorylase a by fructose 1-phosphate (14). These potentially serious manifestations of HFI arise from the inability of the body to degrade fructose and the subsequent impairment of glucose homeostasis (15).