The results of a meta-analysis published in the February 19, 2008 issue of the Annals of Internal Medicine found that N-acetylcysteine works better than other agents to help prevent kidney damage (nephropathy) caused by iodine-containing dyes known as contrast agents which are used to enhance the visualization of organs or other structures during CT scans, angiograms and other imaging scans. Contrast-induced nephropathy is diagnosed when blood creatinine, an indicator of kidney function, increases 25 percent or more within 48 hours following contrast agent administration.
For the review, Aine Kelly, MD, MS, and her University of Michigan colleagues selected 41 randomized, controlled trials that compared the protective ability of a control agent such as saline to N-acetylcysteine, theophylline, fenoldopam, dopamine, iloprost, statin, furosemide, or mannitol in a group of patients in which intravenous iodinated contrast agents were used. The analysis did not include studies involving non-iodinated contrast agents such as barium or gadolinium.
Of the agents analyzed, only N-acetylcysteine was clearly shown to help prevent contrast-induced nephropathy. Although theophylline was found to reduce nephropathy risk more than saline, the amount was not enough to be considered significant. One drug, furosemide, actually increased kidney damage risk.
Elderly individuals and those with diabetes or heart failure have the greatest risk of experiencing contrast-induced nephropathy, and could benefit the most from prophylactic N-acetylcysteine use. Mild to moderate kidney damage occurs following CT scans in one in four of these high-risk individuals. Even among those with normal kidney function, an estimated one in ten experiences some kidney damage from the use of these contrast agents. Dr Kelly recommended that men and women with impaired kidney function speak up when their physician orders a CT scan or angiogram to ensure that they are given an N-acetylcysteine tablet beforehand. Healthy individuals may wish to request that their blood creatinine levels be tested prior to undergoing these scans, in order to ascertain whether they have any unknown kidney impairment.
"Millions of people receive contrast agent each year, including most heart patients who have angioplasties and stents, as well as those having a CT scan. Contrast agent helps physicians see the things we need to see, but it also does pose a hazard to some people," Dr Kelly stated. "This drug, which is quick, convenient, inexpensive and widely available, with no major side effects, appears to be the best choice to protect those whose kidneys are most at risk."
Related Health Concern: Kidney disease
If you have healthy kidneys, protect them. Start with a healthy diet; drink lots of water; give careful attention to the over-the-counter medicines you take, particularly when combined with prescription medicines or other over-the-counter products; consume alcohol responsibly (remember, over-the-counter or prescription drugs can be very damaging to the kidneys when combined with alcohol); protect your kidneys from injury if you engage in sporting activities; and consider taking protective supplements and nutrients to support overall kidney health.
As part of an annual physical checkup, request tests for blood levels of creatinine and blood urea nitrogen and urine levels of protein. Small elevations of creatinine can be an early sign of kidney disease. Early detection leads to early treatment which can occur at a stage when there is treatment to help prevent kidney disease from advancing to a more serious stage.
Dietary supplements are often recommended by physicians and renal dietitians (National Kidney Foundation 2001e). Their recommendations are guided by the results of blood tests that you will be required to take regularly as part of monitoring your condition and treatment results. Always speak with your physician or renal dietitian before using or adding any supplements or herbal products.
In addition to eating a diet that contains appropriate nutrients and levels of protein, a comprehensive multivitamin is often required to replace vitamins that are lost during dialysis treatments (National Kidney Foundation 2001e).
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