Acute kidney injury (AKI) following exposure to iodinated radiocontrast media used for multiple medical imaging procedures including contrast-enhanced computed tomography and coronary and noncoronary angiography represents one of the most common forms of iatrogenic AKI. Multiple mechanisms are believed to contribute to the nephrotoxicity of these agents, including intrarenal vasoconstriction, hyperosmolality, generation of reactive oxygen species, and direct cytotoxicity. The most important risk factor for development of contrast-associated AKI following contrast exposure is preexisting kidney dysfunction. Other patient-related risk factors include concomitant diabetes mellitus, congestive heart failure, volume depletion, and concomitant administration of other nephrotoxic agents, particularly nonsteroidal anti-inflammatory drugs. The toxicity of iodinated contrast media is related to their osmolality, with higher nephrotoxicity associated with higher osmolal contrast media as compared with low-osmolal contrast media and iso-osmolal contrast media. Other risk factors include the volume of contrast media infused, intra-arterial as compared with intravenous administration, and repeated exposure to contrast media over a short period of time. The primary strategy to mitigate the risk of contrast-associated AKI is periprocedural administration of isotonic crystalloid solutions, although the optimal rate of fluid administration is not known. It is also uncertain whether the use of isotonic sodium bicarbonate provides greater renal protection than isotonic saline. Although periprocedural administration of multiple pharmacological agents, including N-acetylcysteine, adenosine antagonists, statins, and ascorbic acid, have been proposed for prevention of contrast-associated AKI, the true effectiveness of these agents remains uncertain. Other pharmacological agents, including loop diuretics, mannitol, and dopamine, and other dopaminergic agonists, as well as prophylactic hemodialysis and hemofiltration, are not effective at reducing the risk of contrast-associated AKI.
