Contrast-Induced Nephropathy: From Pathophysiology to Preventive Strategies

Contrast-induced nephropathy (CIN) is a frequent cause of acute kidney injury in hospitalized patients. CIN is most commonly defined as either an absolute (≥ 0.5 mg/dL; ≥ 44 μmol/L) or relative (≥ 25%) increase in serum creatinine levels at 48-72 hours after exposure to iodinated contrast media (CM). Its occurrence is associated with worsened clinical outcomes. Patients undergoing cardiac catheterization and percutaneous coronary intervention are particularly vulnerable to CIN. The complex pathophysiology of CIN involves different mechanisms, such as vasoconstriction, oxidative stress, medullary ischemia, and the direct toxic effects of CM. In CIN pathophysiology, both patient-related and procedure-related risk factors have been identified. The risk for CIN can be reliably estimated with clinical scores such as that proposed by Mehran. Because no definitive treatment exists for CIN, the most effective strategy remains prevention. Several interventions have been investigated--from hydration to various pharmacologic agents and mechanical devices. In this state-of-the-art article, we review the pathophysiology, diagnosis, risk stratification, and preventive strategies for CIN.