GPX4 and myeloid sarcoma: Therefore, the aim of the present study is to analyze circulatory molecular indicators of all main processes associated with ferroptosis: lipid peroxidation (MDA, 4-HNE, and HEL), GSH-related antioxidant defense (total glutathione (GSH + GSSG), GSH, GSSG, GSH/GSSG ratio and GPX4) and iron metabolism (free iron, transferrin and ferritin), in RRMS and PMS patients, in order to evaluate their contribution to the clinical manifestation of MS and differences between RR and progressive course of disease.