Use and Misuse of a Biomarker: Contrast-Medium-Induced Nephropathy and Serum Creatinine

Two different types of contrast media are being used: low-osmolar and isoosmolar contrast media (LOCM, IOCM). Both types induce renal failure. Serum creatinine is routinely used as a marker of renal impairment in many clinical settings. A variety of studies and meta-analyses addressed the differential safety of contrast media with divergent osmolarity. Unfortunately, research in this field is lacking standardized endpoints, as different levels of creatinine increase are used as a surrogate for renal failure, and additionally, serum creatinine levels are influenced by a variety of pathophysiological conditions and thus susceptible for marker artifacts. This is one explanation why conflicting results have been published regarding the different safety of contrast media favoring either LOCM or IOCM. Viscosity which is higher in IOCM rather than osmolarity determines the potential of a CM to induce renal failure. High viscosity reduces flow in renal tubules and vessels and thus impairs renal filtration. Thus, the most effective prevention measure for renal failure is reducing the concentration of contrast media and adequate hydration. In emergency situations, hydration as well as kidney status is commonly unknown, and LOCM are indicated due to their lower viscosity and to their greater water-binding capacity to reduce the risk of renal failure.