Contrast agent nephrotoxicity. An appraisal.

Impairment of renal function occasionally occurs following the administration of intravascular contrast agents. As a consequence even intravenous urography in the investigation of renal failure was until 20 years ago generally considered to be contraindicated. In the United Kingdom in recent years this extreme view has been rejected and high dose intravenous urography is frequently performed on patients in renal failure. Contrast agent nephrotoxicity has not been frequently encountered. Experience in the United States, however, has been different, a worryingly frequent impairment of renal function after contrast administration being reported by several authors. The reason for this different experience is unclear but it may be the result of patient selection and preparation or contrast dose regime. The United States studies indicate that the patients most at risk are those with already impaired renal function, diabetics and the elderly. A brief review of the literature is given and a classification of possible mechanisms of nephrotoxicity is proposed. It is argued that on the basis of any or all of these mechanisms the low osmolality contrast agents would be expected to be less nephrotoxic than the conventional agents. This suggests that their use should be considered in those patients defined as high risk.