Contrast media induced nephropathy: definition, incidence, outcome, pathophysiology, risk factors and prevention.

Iodanated contrast media related nephrotoxicity is a common phenomenon, which has been known for over five decades now and is widely termed contrast media induced nephropathy (CIN). CIN is one of the most common reasons for hospital-acquired acute kidney injury. The incidence of CIN varies widely, depending on the diagnostic criteria and on the individual risk factors for CIN. CIN is associated with a significant increase in mortality. The clinical features and the histological morphology of CIN are well characterized, whereas the precise mechanisms of renal injury during CIN are not clear. Most likely a combination of different pathomechanisms is involved: contrast media induced reduction of renal perfusion, reduction of tubular flow and direct tubular toxicity leading to a decrease of glomerular filtration rate. Several risk factors for the development of CIN exist, which can be divided into patient related and non-patient related risk factors as well as in modifiable and non-modifiable risk factors. Among them pre-existing renal failure is the most critical parameter. There is no effective treatment for CIN, however, because the development of CIN is predictable, preventional strategies for CIN have been developed. They can be divided into four different categories: volume expansion before, during and after contrast media administration, pharmacological strategies to prevent reduction of renal perfusion, reduction of tubular flow and direct tubular toxicity, renal replacement therapy, and selection of contrast media. Among them, volume expansion is the most critical measure for reducing CIN and should be used in all patients undergoing contrast media procedures.