Today, hospitals are being confronted with increasing costs for additional safety measures. Not all of these measures are evidence-based; for example, the Dutch practice guidelines on the prevention of contrast-induced nephropathy were implemented in recent years, but their long-term efficacy and any possible harm caused by these protocols are not well known. Many questions remain about the exact mechanisms of contrast-induced damage to the kidney. The current protocols recommending preventive hydration have a great impact on costs and hospital management, because an increasing number of patients need to be admitted. More evidence on the efficacy of such preventive measures is needed before we start spending large sums of money following new practice guidelines of which the efficacy has not been adequately substantiated.