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The choice of which intravenous solution to use during tests with dye injected to visualize internal organs or the vascular system can make a difference as to whether or not kidney damage will occur.
According to a report in the April issue of the American Journal of Kidney Diseases, the official journal of the National Kidney Foundation, a mixture of water and sodium bicarbonate - the ingredient in baking soda - is safer than a low-salt solution called saline.
Radiocontrast agents are a type of medical contrast medium (dye) used to improve the visibility of internal bodily structures in imaging techniques such as computed tomography (CT) or X-ray imaging. Modern contrast agents are typically based on iodine. Most often they are used intravenously.
"Contrast-induced nephropathy may occur when the filtering units of the kidney are damaged," explained Dr. Bryan N. Becker, MD, president of the National Kidney Foundation. "This damage allows protein normally kept in the blood plasma to leak into the urine in large amounts. Since the protein in the blood helps keep fluid in the bloodstream, this type of kidney injury can also be associated with swelling or edema."
If severe enough, contrast-induced nephropathy can cause kidney failure that requires kidney dialysis to help remove toxins from the blood, or a transplant.
To minimize the risk of contrast-induced nephropathy, various actions can be taken if the patient has predisposing conditions. Three factors have been associated with an increased risk of contrast-induced nephropathy: preexisting renal insufficiency, diabetes and dehydration.
Individual studies have been unable to prove which hydrating solution is safer when contrast dye is used, so Dr. Sankar D. Navaneethan, a kidney specialist at the Glickman Urological & Kidney Institute at the Cleveland Clinic in Ohio, and co-investigators pooled data from a dozen published clinical trials to clarify this question. Altogether, 1,854 patients were included in the studies.
The combined results showed that sodium bicarbonate-based hydration solutions cut the risk of nephropathy by more than half, the investigators report. Results were similar for patients who already had decreased kidney function prior to the test. The authors also observed that sodium bicarbonate was safe in patients who had heart disease.
"This is very promising but additional studies are needed to determine the optimal regimen of baking soda that will reduce the need for dialysis," said Sonal Singh, M.D., M.P.H., an assistant professor of internal medicine at Wake Forest University School of Medicine and a co-author on the study.