How can we be sure that renal dysfunction after coronary angiography is just explained by contrast nephropathy?
Authors: Caterina Canavese, Fabio Morra, Veronica Morellini, Elisa Lazzarich, Maddalena Brustia, Mario Bo, Piero Stratta
Journal: Kidney International (2004)

To the Editor: A review has been performed on the very hot topic of the role of N-acetylcysteine (NAC) on contrast nephropathy (CN)1Pannu N. Manns B. Lee H. Tonelli M. Systematic review of the impact of N-acetylcysteine on contrast nephropathy.Kidney Int. 2004; 65: 1366-1374Abstract Full Text Full Text PDF PubMed Scopus (239) Google Scholar, of great clinical impact as a result of the CN-linked role in worsening prognosis and increasing costs. The authors wrote that they “assess the efficacy of NAC for preventing CN after …intravenous contrast media,” and concluded that “NAC may reduce the incidence of increased creatinine after administration of intravenous contrast, but this was of borderline statistical significance.” However, both sentences are wrong and misleading, as are similar conclusions reached by another meta-analysis2Kshirsagar A.V. Poole C. Mottl A. et al.N-acetylcysteine for the prevention of radiocontrast induced nephropathy: A meta-analysis of prospective controlled trials.J Am Soc Nephrol. 2004; 15: 761-769Crossref PubMed Scopus (215) Google Scholar, because all 151Pannu N. Manns B. Lee H. Tonelli M. Systematic review of the impact of N-acetylcysteine on contrast nephropathy.Kidney Int. 2004; 65: 1366-1374Abstract Full Text Full Text PDF PubMed Scopus (239) Google Scholar or 162Kshirsagar A.V. Poole C. Mottl A. et al.N-acetylcysteine for the prevention of radiocontrast induced nephropathy: A meta-analysis of prospective controlled trials.J Am Soc Nephrol. 2004; 15: 761-769Crossref PubMed Scopus (215) Google Scholar reviewed papers regarded coronary angiography (CA), except one3Tepel M. Van Der Giet M. Schwarzfeld C. et al.Prevention of radiographic-contrast-agent-induced reductions in renal function by acetylcysteine.N Engl J Med. 2000; 343: 180-184Crossref PubMed Scopus (1437) Google Scholar. First of all, to perform CA, contrast media are introduced into the arterial vascular bed, and not intravenously, as when performing computed tomography (CT). Second, mechanisms of renal dysfunction after CA are not only caused by CN, but also by other causes such as, for instance, cholesterol crystal embolization. We suggest that: (1) further studies be analyzed by separating prevention strategies for CT from those for CA; (2) for CA, attempts will be made to dissect other causes of renal damage by looking for the blue toes syndrome or eosinophilia, in order to exclude cholesterol embolization; (3) even urea increase was considered as end point, to avoid the possibility that creatinine changes might be resulting simply from a direct effect of NAC4Hoffmann U. Fischereder M. Kruger B. et al.The value of N-acetylcysteine in the prevention of radiocontrast agent-induced nephropathy seems questionable.J Am Soc Nephrol. 2004; 15: 407-410Crossref PubMed Scopus (283) Google Scholar. The only quoted paper regarding the use of NAC before performing CT did demonstrate a protection, by also using urea values as end point3Tepel M. Van Der Giet M. Schwarzfeld C. et al.Prevention of radiographic-contrast-agent-induced reductions in renal function by acetylcysteine.N Engl J Med. 2000; 343: 180-184Crossref PubMed Scopus (1437) Google Scholar.