Mitochondrial dysfunction and serum lactate as a biomarker for the progression and disability in MS and its correlation with the radiological findings.

: To study the serum lactate level in MS and to explore its correlation with the progression and disability in multiple sclerosis (MS), and the important role of mitochondrial dysfunction in the pathogenesis of MS.: This case-control study included 80 participants, involved 50 MS patients and 30 normal healthy controls. Detailed history taking, complete neurological examination, and clinical evaluation of the disability using the Expanded Disability Status Scale (EDSS) were done for all patients. Level of serum lactate was measured in both groups and was correlated with EDSS, MS subtypes, MRI brain, and MRS findings.: Serum lactate in MS patients was about three and half times higher than serum lactate levels of healthy controls (22.87 ± 5.92 mg/dl versus 6.39 ± 0.9 6.39 ± 0.91, p < 0.001). Importantly, serum lactate values were increased in MS cases with a progressive course compared with MS cases with RR course. Also, there were linearly correlations linking serum lactate levels and the duration of MS (r = 0.342, P = 0.015), relapses numbers (r = 0.335, P = 0.022), and EDSS (r = 0.483, P < 0.001). Also, there were strong positive correlations between serum lactate and Lipid/Lactate (r = 0.461, P = 0.001), periventricular lesion (r = 0.453, P = 0.005), and moderate positive correlations between serum lactate and juxtacortical lesion (r = 0.351, P = 0.02), and infratentorial lesion (r = 0.355, P = 0.02).: Measurement of serum lactate may be helpful in MS and this supports the hypothesis of the critical role of mitochondrial dysfunction and axonal damage in MS.: ClinicalTrials.gov ID: NCT04210960.