[Pathophysiology of contrast-induced nephropathy].

Contrast-induced nephropathy is one of the major causes of kidney failure in hospitalized patients. Its increased frequency is due to the high number of invasive procedures using contrast media performed for diagnostic or therapeutic purposes in patients with cardiovascular diseases with advanced age and chronic comorbidities such as diabetes and preexisting renal failure. There are two main causes of contrast-induced nephropathy: the direct toxic effect of contrast media on kidney tubules (as shown by morphologic alterations of these cells) and the tissue hypoxia of the renal medulla, secondary to the hemodynamic effects brought about by these agents, consisting in a reduction of vascular resistances. In vulnerable patients, these vasoconstrictor effects are not balanced by an effective vasodilatory reserve and probably by a reduced production of antiapoptotic proteins.