Contrast Media-Associated Nephrotoxicity: A Narrative Review of Pathophysiology, Risk Factors, Prevention, and Clinical Management

Background: Contrast media are essential tools in diagnostic and interventional imaging, but their relationship with acute kidney injury remains clinically relevant and conceptually debated. This narrative review aimed to synthesize current evidence on contrast media-associated nephrotoxicity, including terminology, epidemiology, pathophysiology, risk stratification, prevention, pharmacotherapeutic management, and clinical decision-making. Methods: A structured literature search was conducted in major biomedical databases and complemented by international guidelines and consensus statements addressing contrast-associated and contrast-induced acute kidney injury in adults exposed to intravascular contrast media. Discussion: Contemporary evidence emphasizes the distinction between contrast-associated acute kidney injury, which reflects a temporal association after exposure, and contrast-induced acute kidney injury, which implies causality. The renal risk directly attributable to modern intravenous iodinated contrast media appears to have been historically overestimated, although clinically relevant risk persists in vulnerable patients. Proposed mechanisms include renal vasoconstriction, medullary hypoxia, oxidative stress, mitochondrial dysfunction, tubular epithelial injury, endothelial dysfunction, and inflammatory or apoptotic pathways. Preventive strategies should be individualized, with isotonic saline remaining the main intervention when indicated, whereas routine pharmacologic prophylaxis is not supported by consistent clinically meaningful benefit. Conclusions: Renal safety in contrast-enhanced imaging requires a balanced approach that minimizes avoidable kidney injury in high-risk patients without unnecessarily delaying clinically indicated diagnostic or therapeutic procedures.