Should we screen MDCT patients for risk of CIN?

A small percentage of patients referred for imaging procedures involving administration of contrast media (CM) are at risk for contrast-induced nephrotoxicity (CIN), a complication that can be fatal. It is therefore important to identify those at greatest risk so that precautionary measures can be taken. However, routine screening to identify high-risk individuals is highly variable among institutions that perform computed tomography (CT), and many referring physicians are not fully aware of the risks associated with CM-enhanced imaging procedures. Assessment of the presence of risk factors (e. g. renal disease, diabetes, hypotension) can help identify patients at risk who warrant further investigation. Although measurement of serum creatinine (SCr) level is commonly used to estimate renal function, it is not an ideal marker. Because SCr depends on muscle mass and is not usually elevated until the glomerular filtration rate (GFR) has fallen by at least 50%, it can underestimate renal dysfunction, particularly in women and the elderly. In contrast, GFR is a more accurate measure of renal function in most patients. The value of using GFR to identify patients at risk of CIN has been demonstrated in a retrospective review of 561 patients undergoing CM-enhanced CT. This study found that SCr identified 11.8% of patients as being at risk for CIN, whereas GFR identified 24.8% of patients as being at risk. In conclusion, accurate assessment of patients at risk for CIN should be performed prior to administering CM and should probably involve calculation of GFR and SCr.