Characterization of the oxidative metabolism in lactate dehydrogenase A deficiency

Recurrent rhabdomyolysis due to decreased glycolysis occurred during strenuous exercise in patients with lactate dehydrogenase A subunit (LDH-A) deficiency. We report the features of oxidative metabolism of four patients from two families in whom the severity of the disease differed. Enzyme activities of muscle LDH were decreased to < 5% of control. There was no difference in the gene abnormality. Maximal oxygen uptake in the patients with severe and mild symptoms was approximately 73% and 92% of control. Respiratory exchange ratio was increased to more than 1.0 during maximal exercise. These findings suggest that in these patients, the oxidative functions of glycogenolysis in which pyruvate is required for fuel of maximal oxidative metabolism are preserved, and that disease severity may be related to the degree of muscle oxidative capacity.