S-cystatin C formulae or combination of s-cystatin C and s-creatinine formulae do not improve prediction of GFR.

of the NEPHRIC trial (n = 129 patients), which shows a smaller incidence of contrast-induced nephropathy by using iso-osmolar contrast media [2]. However, we also have not changed our routine daily clinical approach in 2008 by using the low-osmolar contrast media, because the published results were conflicting in the last 2 years. In our paper, we emphasized these conflicting results concerning the value of the osmolality of a contrast media (iso-osmolar versus low-osmolar) in preventing contrastinduced nephropathy by citing three recent trials (RECOVER with n = 300 patients published in 2006, IMPACT with n = 166 patients published in 2006 and CARE with n = 414 patients published in 2007). It was described by the authors of the RECOVER trial, Jo et al., that they indeed found a benefit regarding the composite end-point. Regarding the end-point defined by Aspelin et al. in the NEPHRIC trial, no benefit of the isoosmolar contrast media could be demonstrated [3]. In the IMPACT and the CARE trial there were no different rates of contrast-induced nephropathy by the use of lowversus iso-osmolar contrast media [4,5]. The CARE trial is the most recent and largest, prospective, randomized double-blind trial comparing the iso-osmolar iodixanol370 with the low-osmolar iodixanol-320: when a composite end-point was assessed, the rate of contrast-induced nephropathy was not significantly different (10.3% versus 12.9%) after the administration of the different contrast media [5]. From our point of view, the results are so conflicting that there is no evidence of the superiority of the iso-osmolar versus the low-osmolar contrast media and no firm recommendation based on the overwhelming majority of evidences can be made.