[Na/Fe] corrected for non-LTE versus [Fe/H] for our Sculptor sample (red asterisks), extremely metal-poor halo stars (Andrievsky et al. 2007, black filled circles), two other stars in the Sculptor dSph and one in the Fornax dSph from Tafelmeyer et al. (2010) and three stars in Carina from Venn et al. (2012) (red triangles, gray circle and gray crosses respectively). A typical error bar for the Milky Way stars is shown in the bottom left corner of the figure.