Contrast-induced nephropathy

Mark O. Baerlocher; Murray Asch; Andy Myers

doi:10.1503/cmaj.090372

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Medical school admissions
Mark Otto Baerlocher

Posted on: 14 October 2010
Route of contrast administration matters
Swapnil Hiremath

Posted on: 08 October 2010

Posted on: (14 October 2010)

Medical school admissions
Mark Otto Baerlocher, Toronto, Ont.
We thank Dr. Hiremath for his thoughtful letter and suggestions.
The editorial which Dr. Hiremath has referenced in his first point (1) is indeed thought provoking. There is admittedly a feeling amongst some clinicians that the current guidelines regarding use of contrast media may be too stringent; however, there are insufficient data to dogmatically state that the practice points (based on ACR, CAR and ESUR...
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We thank Dr. Hiremath for his thoughtful letter and suggestions.
The editorial which Dr. Hiremath has referenced in his first point (1) is indeed thought provoking. There is admittedly a feeling amongst some clinicians that the current guidelines regarding use of contrast media may be too stringent; however, there are insufficient data to dogmatically state that the practice points (based on ACR, CAR and ESUR guidelines) mainly apply to intraarterial contrast. We're confident that any practicing radiologist has seen their fair share of CIN cases from CT scans (which involve intravenous, not intraarterial administration of contrast). Given the choice between following the guidelines and potentially withholding contrast unnecessarily or applying the guidelines only to intraarterial use of contrast and potentially risking CIN in at-risk patients receiving intravenous contrast, we prefer to follow the more conservative option. Of course we look forward to a time when the medical community's understanding of the complex interaction between contrast media and renal function is more complete and we hope then to be able to safely and confidently offer contrast to a greater number of patients.
Regarding his second point, we agree that contrast-enhanced MRI scans are indeed not entirely without risk, particularly in patients at increased risk. The at-risk groups are quite different, as we are sure Dr. Hiremath will agree.
Regarding n-acetylcysteine, Dr. Hiremath makes a good point that the final word on its effectiveness is yet to be determined. Clearly, hydration is the mainstay in preventing CIN. Our general view, however, is that NAC has such a low risk profile that there is little harm in administering the medication in hopes of providing any additional protection it may confer.
Mark O Baerlocher Andy Myers Murray R Asch
Conflict of Interest:
None declared
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Competing Interests: None declared.
Posted on: (8 October 2010)

Route of contrast administration matters
Swapnil Hiremath
The 5 practice points about Contrast-induced Nephropathy - now more commonly referred to as Contrast-Induced Acute Kidney Injury (CI-AKI) – were timely and fairly accurate. However, the authors refer to ‘intravascular contrast’ as being the cause of CI-AKI. There is a clear distinction between intraarterial contrast use (eg with cardiac catheterization and other angiography procedures) and intravenous contrast use (eg c...
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The 5 practice points about Contrast-induced Nephropathy - now more commonly referred to as Contrast-Induced Acute Kidney Injury (CI-AKI) – were timely and fairly accurate. However, the authors refer to ‘intravascular contrast’ as being the cause of CI-AKI. There is a clear distinction between intraarterial contrast use (eg with cardiac catheterization and other angiography procedures) and intravenous contrast use (eg computed tomography), with the risk being much higher for the former (1). Thus, the practice points apply mainly to intraarterial contrast use and their application to contrast-enhanced computed tomography scans may result in unnecessary avoidance of a useful and relatively safe investigation. This is all the more concerning since one of the alternative imaging options suggested, magnetic resonance imaging, is also not completely safe in patients with severe chronic kidney disease (2). Lastly, there is indeed disagreement about the efficacy of n- acetylcysteine mainly due to conflicting results in small under-powered studies; but the most meticulous meta-analysis published on this topic suggests that it is not efficacious (3). It would be prudent, however, to withhold comment on its efficacy until the results of an adequately powered study (4) on this issue are available, which should be in November 2010 (5).
References: 1. Katzberg RW, Newhouse JH. Intravenous contrast medium-induced nephrotoxicity: is the medical risk really as great as we have come to believe? Radiology. 2010 Jul;256(1):21-8. 2. Kroshinsky D, Kay J, Nazarian RM. Case records of the Massachusetts General Hospital. Case 37-2009. A 46-year-old woman with chronic renal failure, leg swelling, and skin changes.N Engl J Med. 2009 Nov 26;361(22):2166-76. 3. Gonzales DA, Norsworthy KJ, Kern SJ, Banks S, Sieving PC, Star RA, Natanson C, Danner RL. A meta-analysis of N-acetylcysteine in contrast- induced nephrotoxicity: unsupervised clustering to resolve heterogeneity. BMC Med. 2007 Nov 14;5:32. 4. ACT Trial Investigators. Rationale, design, and baseline characteristics of the Acetylcysteine for Contrast-Induced nephropaThy (ACT) Trial: a pragmatic randomized controlled trial to evaluate the efficacy of acetylcysteine for the prevention of contrast-induced nephropathy.Trials. 2009 Jun 4;10:38. 5. http://scientificsessions.americanheart.org/portal/scientificsessions/ss/lbct , accessed Oct 6 2010.
Conflict of Interest:
None declared
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Competing Interests: None declared.