What is the best definition of contrast-induced nephropathy?

Radiological procedures require the intravascular administration of iodinated contrast media, which are becoming a great source of an iatrogenic disease known as contrast-induced nephropathy. The development of contrast-induced nephropathy is associated with prolonged hospitalization, the potential need for renal replacement therapy, and increased mortality. Despite numerous clinical and experimental studies, several important issues regarding contrast-induced nephropathy remain controversial. One of the controversial points is its very definition: a universally accepted definition of contrast-induced nephropathy does not exist. This can be a major problem. Differing definitions of contrast-induced nephropathy and the clinical importance of these definitions were discussed in this letter.