A variety of prophylactic approaches have been investigated. Despite nephro-protective effects of hydration with saline or with sodium bicarbonate, other trials reported CIN-incidences between 20 and 50% despite hydration. Several studies and two recent meta-analyses demonstrated a significant reduction of renal impairment after contrast-medium using medical prophylaxis with the adenosine antagonist theophylline. However, a recent trial failed to prove prophylactic effects of theophylline.