SA Journal of Radiology

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Potential mechanisms behind contrast medium-induced nephropathy

PB Persson, A Patzak


How contrast medium-induced nephropathy (CIN) comes about is poorly understood, although CIN is a common cause of acute renal failure. Hitherto, the
various studies performed have led to different interpretations and partially contradictory
conclusions. This article aimed to review the mechanisms underlying CIN and to outline existing data obtained with the newer iodinated agents in patients with pre-existing renal failure. Osmolality, which has received considerable attention, is but one of several physico-chemical properties of contrast media (CM). The more recently developed iso-osmolar CM
are dimers, not monomers as the widely used non-ionic low osmolar CM. Thus, in
spite of them being iso-osmolar, they have physicochemical features different from
other CM, e.g. in terms of viscosity (> 5 fold greater than plasma viscosity), which
may be of considerable pathophysiologic and clinical importance. Many experimental
studies provide evidence for greater perturbation in renal function with iso-osmolar
CM compared with non-ionic lowosmolar CM. Conversely, some clinical trials
indicate an advantage of the iso-osmolar CM, although others do not. In this
review, the possible causes of CIN are highlighted, including altered rheological properties,
perturbation of renal haemodynamics, regional hypoxia, auto- and paracrine factors (adenosine, endothelin, reactive oxygen species) and direct cytotoxic effects.
It is concluded that caution must be taken to avoid a false sense of security with the
use of iso-osmolar CM.

South African Journal of Radiology Vol. 9 (3) 2005: pp. 26-28

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