What is CIN?
CIN is defined as an acute reduction in renal function secondary to iodinated contrast material administration. For practical purposes, however, this definition begs the questions of how this reduction in renal function is measured; what threshold is used to declare that a particular patient has developed CIN; and how it is determined that iodinated contrast material, and not something else, is the cause. Most CIN studies in the literature have used serum creatinine (SCr) as the proxy measure of renal function. This is largely because SCr measurement is relatively inexpensive and widely available. Recently, there has been some groundswell to use a calculated estimation of renal function, the estimated glomerular filtration rate (GFR), as the index measurement [4]. Unfortunately, there are serious problems with the use of either SCr or estimated GFR as indicators for the development of CIN. One basic issue is that even if renal function could be measured precisely, there is no universal
