Oxidative stress markers
Native thiol (NT), total thiol (TT) and disulfide (DS) levels were analyzed according to the method of Erel and Neselioglu.8 DS (S-S) levels were determined by calculating half of the difference between TT (-SH+S-S) and NT (-SH); subsequently, DS/NT, DS/TT, and NT/TT ratios were calculated.8
Serum TAS and TOS levels were measured using the automated colorimetric method developed by Erel O.13,14 After measuring the TOS and TAS levels, as a further good marker of oxidative stress, the oxidative stress index (OSI) was calculated as follows: OSI= [(TOS /TAS)×100].15