Elimination Rate of Serum Lactate is Correlated with Amyotrophic Lateral Sclerosis Progression

Background: Mitochondrial dysfunction plays an important role in the pathogenesis of amyotrophic lateral sclerosis (ALS). We aimed to demonstrate mitochondrial dysfunction in ALS using a lactate stress test and to examine the relationship between mitochondrial dysfunction with motor deterioration. Methods: We enrolled 116 patients and observed clinical variables, including the survival state. Results: Patients with a rapid slope of revised ALS functional rating scales (ALSFRS-r) (>20 U/year) exhibited the slowest elimination rate (median −4.67 × 10−3 mmol·L−1·min−1 , coefficient of variation, 590.15%), the shortest duration (0.63 ± 0.28 years) and the worst ALSFRS-r (32.59 ± 4.93). Patients with a moderate slope of ALSFRS-r (10-20 U/year) showed a moderate elimination rate (median −11.33 × 10−3 mmol·L−1·min−1 , coefficient of variation, 309.89%), duration (1.16 ± 0.45 years), and ALSFRS-r (34.83 ± 6.11). The slower progressing (