Contrast-induced nephropathy (CIN) was first recognized more than 50 years ago. 1 Contrast media have changed over time to become increasingly safe and well tolerated, but the indications for use of contrast media have greatly expanded. In addition, the number of patients with risk factors for CIN has also increased. The result is that CIN has become an increasing burden on health care resources.

There are now more than 25,000 CT scanners worldwide. The number of CT examinations performed annually has increased as improvements in technology have created new indications for CT and CT angiography. In the past 2 decades, CT scanning has increased 800%. 2 In the United States alone, 50 million CT procedures are performed annually, and approximately 50% of CT examinations use contrast.2 The expansion in the use of contrast media has not been limited to radiology procedures. Cardiac catheterization and percutaneous coronary intervention (PCI) increased 390% between 1979 and 2002; more than 1.4 million cardiac catheterizations were performed in 2000 in the United States. 3 Similar data apply for Europe, where cardiac catheterization increased 112% over the past decade, with 1.8 million catheterizations performed in 2001. 4

The risk factors for CIN have also increased in prevalence over this time. Diabetes and chronic renal insufficiency are increasingly common. More than 20 million people have some chronic renal insufficiency in the United States. 5 Prevalence is greatest among the elderly, with more than 30% of individuals over the age of 60 years having some degree of renal insufficiency.5 The burden of diabetes is also increasing throughout the world, with almost 200 million individuals affected and a projected increase in prevalence of 75% over the next 20 years. 6

The patient who develops CIN is at risk for a number of adverse events. Data derived from experience in treating cardiac patients indicate that there is a twofold-to-fivefold increase in mortality while patients are in the hospital, mostly related to an increase in adverse cardiac events. Hospital resource consumption is increased, as well. Hospital lengths of stay increase from 5 to 10 days for CIN patients, use of dialysis facilities increases 10% to 15%, and there are scheduling delays for additional procedures, all of which affect costs. 7 Long-term mortality (at 1 year) also increases threefold. 8,9 Similar data collected for a wide variety of patients, including those undergoing CT examinations, support the finding that there is increased mortality among individuals who develop CIN. 10

The consequences of this adverse event require a coordinated approach to management. CIN is a predictable event, occurring immediately after exposure to contrast media (both iodinated contrast and gadolinium compounds) in vulnerable individuals. Its incidence is 10% to 50% in susceptible individuals receiving cardiac angiography, rising in parallel with the baseline serum creatinine level. 11 The incidence for CT studies is less clear. One prospective trial 12 for abdominal CT found a 21% incidence in patients with a baseline glomerular filtration rate of less than 50 mL per minute. Incidence in patients with lesser degrees of renal insufficiency is unknown.

Appropriate management involves identifying vulnerable individuals before contrast exposure and employing strategies to minimize the occurrence of CIN. Chronic kidney disease is the most important risk factor, but it does not explain all CIN. Risk profiling has been advanced for both cardiac and CT patients. A protocol-driven approach using risk assessment will help to minimize the occurrence of CIN without compromising patient throughput.

Strategies to prevent CIN have been developed largely from experience with cardiac patients. These patients have many of the risk factors that make the kidney more vulnerable to contrast effects, and they are usually followed closely after contrast exposure, particularly when PCI has been performed. In these patients, volume expansion with saline, 13,14 minimization of contrast volume, use of low-osmolality or iso-osmolality contrast media, 15,16 and antioxidant therapy have been shown, in prospective controlled trials to reduce the risk of CIN. 17 There is considerably less published information for CT angiography (despite the fact that there are 10 to 20 times as many CT angiography procedures performed as cardiac angiography procedures).

Although a great deal of effort has been made to reduce the incidence of CIN, the best results from clinical trials show a 2% to 5% incidence. It is very likely that incidence is considerably higher in clinical practice, where preventive strategies may be less rigorously applied.

Richard Solomon, MD, is professor of medicine and chief of the Division of Nephrology, University Health Center, Fletcher Allen Health Care, Burlington, Vt.


  1. Bartels E, Brun GC, Gammeltof A, Gjorup LA. Acute anuria following intravenous pyelography in a patient with myelomatosis. Acta Med Scand. 1954;150:297-302.
  2. Kalra M, Maher MM, D’Souza R, Saini S. Multidetector computed tomography technology: current status and emerging developments. J Comput Assist Tomogr. 2004;28(suppl 1):S2-S6.
  3. American Heart Disease and Stroke Statistics-2005 Update: Dallas, Tx, American Heart Association; 2005.
  4. Togni M, Balmer F, Pfiffner D, Maier W, Zeiher AM, Meier B. Percutaneous coronary interventions in Europe 1992-2001. Eur Heart J. 2004;25:1208-1213.
  5. Coresh J, Wei GL, McQuillan G et al. Prevalence of high blood pressure and elevated serum creatinine level in the United States. J Am Soc Nephrol. 2001;161:1207-1216.
  6. Rigalleau J, Lasseur C, Perlemoine et al. Estimation of glomerular filtration rate in diabetic subjects: Cockcroft formula or modification of diet in renal disease study equation? Diabetes Care. 2005;28:838-834.
  7. Iakovou I, Dangas G, Lansky AJ, et al. Incidence, predictors, and economic impact of contrast induced nephropathy: results in 8,628 patients treated with percutaneous coronary interventions. J Am Coll Cardiol. 2002;39:2A.
  8. Gruberg L, Mintz GS, Mehran R, et al. The prognostic implications of further renal function deterioration within 48 h of interventional coronary procedures in patients with pre-existent chronic renal insufficiency. J Am Coll Cardiol. 2000;36:1542-1548.
  9. Rihal C, Textor SC, Grill DE, et al. Incidence and prognostic importance of acute renal failure after percutaneous coronary intervention. Circulation. 2002;105:2259-2264.
  10. Levy E, Viscoli CM, Horwitz RI. The effect of acute renal failure on mortality. A cohort analysis. JAMA. 1996;275:1489-1494.
  11. McCullough P, Sandberg KA. Epidemiology of contrast-induced nephropathy. Rev Cardiovasc Med. 2003;4(suppl 5):S3-S9.
  12. Tepel M, Van Der Giet M, Schwarzfeld C, Laufer U, Liermann D, Zidek W. Prevention of radiographic-contrast-agent-induced reductions in renal function by acetylcysteine. N Engl J Med. 2000;343:180-184.
  13. Solomon R, Werner C, Mann D, et al. Effects of saline, mannitol, and furosemide to prevent acute decreases in renal function induced by radiocontrast agents. N Engl J Med. 1994;331:1416-1420.
  14. Mueller C, Guerkle G, Buettner H, et al. Prevention of contrast media-associated nephropathy: randomized comparison of 2 hydration regimens in 1620 patients undergoing coronary angiography. Arch Int Med. 2002;162:329-336.
  15. Briguori C, Colombo A, Airoldi F, et al. Nephrotoxicity of low-osmolality versus iso-osmolality contrast agents: impact of N-acetylcysteine. Kidney Int (in press), 2005.
  16. Solomon R. The role of osmolality in the incidence of contrast induced nephropathy: a systematic review of angiographic contrast media in high risk patients. Kidney Int. 2005;68:2256-2263.
  17. Kshirsagar A, 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;15:761-769.