During the first 24 hourse of fasting glycogenolysis and gluconeogenesis are used as fuel reservoirs.
Between 1-3 days of starvation FFA is used as a major source of fuel.

If a young patient with MCAD has been fasting for 15 hours, he should not present with severe hypoglycemia since at this point glycogen is being used.
That's my understanding.

However, a question states an 8 yo boy with 15 hrs of fasting presenting with nonketonic hypoglycemia has MCAD.
Please help me understand how, as I would think this patient would have a glycogenolysis dysfunction.

Anyone?

Does the question stem offer any clues as to why he was on a 15 hour fast? Was he laying around watching TV for 15 hours, or was he outdoors being active for 15 hours? There's a big difference and the latter could exasperate symptoms of MCAD.

If the latter is in the question stem, then you should assume the child's body has been using its glycogen stores at an increased rate the entire day and the "24-hour mark" for glycogen will be shifted up a bit. If this is the case, he'll need to rely on catabolism of FAs to Glc or ketones....which is not possible with MCAD Dz.

Thank you so much.
The stem mentioned that the boy was out camping.
Now it makes sense.
I appreciate it so much!