1 Answers
Contrast-induced nephropathy is a purported form of kidney damage in which there has been recent exposure to medical imaging contrast material without another clear cause for the acute kidney injury. CIN is classically defined as a serum creatinine increase of at least 25% and/or an absolute increase in serum creatinine of 0.5 mg/dL after using iodine contrast agent without another clear cause for acute kidney injury, but other definitions have also been used.
Despite extensive speculation, the actual occurrence of contrast-induced nephropathy has not been demonstrated in the literature. The mechanism of contrast-induced nephropathy is not entirely understood, but is thought to include direct damage from reactive oxygen species, contrast-induced increase in urine output, increased oxygen consumption, changes in dilation and narrowing of the blood vessels to the kidneys, and changes in urine viscosity.
Analysis of observational studies has shown that radiocontrast use in CT scanning is not causally related to changes in kidney function. Given the increasing doubts about the contribution of radiocontrast to acute kidney injury, the American College of Radiology has proposed the name post-contrast acute kidney injury does not imply a causal role, with CIN or contrast induced acute kidney injury reserved for the rare cases where radiocontrast is likely to be causally related.