Objective: To evaluate the influence of disease activity, the degree of patient disability and pathogenetic therapy on the concentration of neurofilament light chain (NFL) in the blood serum of patients with multiple sclerosis (MS).

Methods: One hundred and fourteen patients (84 women and 30 men) with definite MS were examined. The concentration of NFL in the blood serum of patients with MS was determined by enzyme immunoassay. The level of NFL was analyzed depending on the characteristics of the course and activity of the demyelinating process, the severity of neurological disorders as well as disease modifying drugs (DMDs).

Results: An NFL level equal to or greater than 4201 pg/ml was found to be associated with a higher risk of developing a clinical exacerbation in the next 4 months. In patients with progression of disability over the next 2 years, the initial concentration of NFL was significantly higher than in the group with a stable EDSS score. The NFL level (4943 pg/ml and higher), which may be a predictor of increased disability in the next two years, was established.

Conclusions: The study demonstrates the possibility of using serum NFL levels as a diagnostic marker of possible exacerbation, as well as predicting disability in patients with MS.