A good way to differentiate between these two conditions is by remembering that in McArdle you have difficulty in the beginning of the exercise while in myopathic carnitine acyl transferase deficiency you have a problem after a prolonged exercise.
The explanation for this is that glycogen is utilized first by muscles as a source of energy so in McArdle (Muslce glycogen phosphorylase deficiency) you have a problem in the beginning and patients will have muscle cramps after few seconds of starting the exercise. However once the beta oxidation kicks in they will experience the classical "second wind".
While in Muslce carnitine deficiency you have a problem later on when Fatty acids oxidation is needed.
Both conditions may have myoglobinuria
In muscle carnitine you'll see accumulated triglycerides in biopsy while in McArdle (also called Type V glycogen storage disease) you will have accumulated glycogen in muscle biopsy.
Both conditions will not cause hypoglycemia because muscles do not release glucose to the tissues as it lacks the glucose 6 phosphates enzyme.
The explanation for this is that glycogen is utilized first by muscles as a source of energy so in McArdle (Muslce glycogen phosphorylase deficiency) you have a problem in the beginning and patients will have muscle cramps after few seconds of starting the exercise. However once the beta oxidation kicks in they will experience the classical "second wind".
While in Muslce carnitine deficiency you have a problem later on when Fatty acids oxidation is needed.
Both conditions may have myoglobinuria
In muscle carnitine you'll see accumulated triglycerides in biopsy while in McArdle (also called Type V glycogen storage disease) you will have accumulated glycogen in muscle biopsy.
Both conditions will not cause hypoglycemia because muscles do not release glucose to the tissues as it lacks the glucose 6 phosphates enzyme.
