Contrast-induced nephropathy

How contrast medium-induced nephropathy (CIN) comes about is not fully understood, although CIN constitutes a leading cause of renal failure. Here, a short review of clinical trials and a more thorough outline of mechanisms thought to cause CIN are outlined. Osmolality is only one of several physicochernical properties of contrast media (CM). Iso-osmolar CM are dimers, not monomers. Thus, they have physicochernical features different from other CM, e.g., in terms of viscosity (which is over fivefold greater than plasma viscosity). This may be of considerable pathophysiologic and clinical importance. There are studies providing evidence for a greater perturbation in renal functions by iso-osmolar CM in comparison to nonionic low-osmolar CM. Conversely, some previous clinical trials indicate an advantage of the iso-osmolar CM. This review highlights altered theological properties, perturbation of renal hemodynamics, regional hypoxia, autoand paracrine factors (adenosine, endothelin, reactive oxygen species) and direct cytotoxic effects, which are all thought to participate in causing CIN. It is concluded that the use of CM in general, and high viscous iso-osmolar CM in particular, can be deleterious to the kidney due to augmented resistance in the renal tubules.