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Will CAT scan damage my kidneys?

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Practicing since : 2003
Answered : 495 Questions
** Please post this question specifically to Dr. XXXXXXX Bhabhe** Hi Dr. XXXXXXX Bhabhe, I had a urinalysis done about a month ago, and all of the blood markers I had tested for came down in number / severity. 7 days ago, I had another Urinalysis done and all the blood markers were negative. That was a relief !! Also my cytology urine report came back negative. Here are my questions. Since I do have a lower functioning kidney, (eGFR of 88), I want to know if there is an imaging technology that poses a lower risk of damaging my kidneys ? I have heard that people with some kidney diseases are more prone to damage if a CAT scan is done with XXXXXXX Do you have any recommendation for alternative dyes, dyes that do not damage kidneys. Dyes that carry a lower risk of damaging kidneys. Whether it be dyes for CAT scans ?, MRI dyes ? Ultra sound ? Thank you, XXXX
Posted Sun, 2 Feb 2014 in General Health
Answered by Dr. Aditya Bhabhe 4 hours later
Brief Answer: See detailed answer Detailed Answer: Hi XXXXXXX Thank you for writing in again. I will answer your query in a sequential manner (discussing each modality): 1) Ultrasound: dyes are not used. This technique has no side effect on the kidneys 2) CT Scan: often requires the use of a dye. We prefer a non-ionic dye As your GFR is 88, the risk of worsening kidney function is minimal (5%) and even if it occurs it would usually be a temporary worsening. You should keep yourself well hydrated before and after the XXXXXXX Some doctors use a tablet called as N Acetyl cysteine (NAC) to further protect the kidneys. Your nephrologist can provide specific details of hydration and NAC. 3) MRI: uses dye but there have been no adverse effects described at a GFR of 88. To summarize we can use any imaging technique which provides the most diagnostic information. If CT scan is advised, follow the instructions as above. I hope this was helpful I will be happy to provide further answers Regards Dr Bhabhe
Above answer was peer-reviewed by
Follow-up: Will CAT scan damage my kidneys? 40 hours later
Hi Dr. XXXXXXX Bhabhe, I found an article, please see below. In the below article, it states: "Mild to moderate kidney damage occurs in one in four high-risk people who have CT scans, and in as many as one in ten people with normal kidney function. In some cases, it causes acute kidney failure." You had mentioned that with a GFR of 88 that there would only be a 5% chance of worsening kidney function. Is the 5% you gave me an updated calculation ? The study given below was reported in 2008, and gave a report stating one in ten people with normal kidney function could develop kidney damage. Please don't see this as a challenge, I am concerned about my kidneys, and I'd like your interpretation of the below article. Thank you and your time is very appreciated. XXXX See article below. Title Before A CT Scan Or Angiogram, Many People Should Take Inexpensive Drug To Protect Kidneys Feb. 20, 2008 — As more and more Americans undergo CT scans and other medical imaging scans involving intense X-rays, a new study suggests that many of them should take a pre-scan drug that could protect their kidneys from damage. The inexpensive drug, called N-acetylcysteine, can prevent serious kidney damage that can be caused by the iodine-containing "dyes" that doctors use to enhance the quality of such scans. That "dye," called contrast agent, is usually given intravenously before a CT scan, angiogram or other test. But the new study shows that taking an N-acetylcysteine tablet before receiving the contrast agent can protect patients -- and that it works better than other medicines that have been proposed for the same purpose. People whose kidneys are already vulnerable, including many older people and those with diabetes or heart failure, are the most at risk from contrast agents, and have the most to gain from taking the drug. Researchers from the University of Michigan Health System performed the study, which is published in the Annals of Internal Medicine. It is a meta-analysis of data from 41 randomized controlled studies that evaluated various drugs for their kidney-protecting effects. It was led by XXXXXXX XXXXXXX M.D., M.S., an assistant professor in the Department of Radiology at the U-M Medical School. Only N-acetylcysteine clearly prevented contrast-induced nephropathy, the medical name for kidney damage caused by contrast agents. Theophylline, another drug that has been seen as a possible kidney-protecting agent, did not reduce risk significantly. Other drugs had no effect, and one, furosemide, raised kidney risk. "Our goal is to improve the safety and quality of these common tests by studying drugs that reduce the risk of kidney failure," says XXXXXXX author XXXXXXX XXXXXXX M.D., associate professor of radiology. *** Mild to moderate kidney damage occurs in one in four high-risk people who have CT scans, and in as many as one in ten people with normal kidney function. In some cases, it causes acute kidney failure. *** "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," says XXXXXXX "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." Only studies that involved intravenous iodine-containing contrast agents, and compared a drug with a water or saline control, were included in the analysis. Oral "milkshake" barium contrast agents, used in CT scans of the digestive system, do not cause kidney damage, and were not included. The study also did not assess potential ways to protect against kidney damage from gadolinium contrast agents used in MRI (magnetic resonance imaging) scans. Since May 2007, those contrast agents have carried a warning from the U.S. Food and Drug Administration about risk to kidneys. XXXXXXX XXXXXXX and their colleagues performed the study to try to get a firm answer to a question that has puzzle medical imaging specialists for years. Although many drugs have been tried for prevention of iodine-related contrast-induced nephropathy, contradictory evidence has emerged from studies of how well they work. The result has been widespread variation in what hospitals and medical imaging centers do before scanning a patient. Although a prospective trial comparing N-acetylcysteine directly to other drugs should be conducted to verify the U-M team's findings, the team hopes its new study will help guide both clinicians and patients. In fact, XXXXXXX says, patients who know they have weakened kidneys -- also called impaired renal function -- should speak up when their doctor orders a CT scan, angiogram or angioplasty, and make sure they get a tablet of N-acetylcysteine beforehand. And, since most kidney problems cause no symptoms, even healthy people might want to ask their doctors to test their blood creatinine levels before sending them for a scan. Creatinine levels go up when the kidneys aren't operating efficiently. Contrast-induced nephropathy is defined as a 25 percent or greater increase in creatinine within 48 hours of receiving contrast agent. The new study evaluated the impact of pre-scan medicines by looking at their impact on patients' creatinine levels, as a surrogate for kidney function. The problem of contrast-induced nephropathy is a relatively recent one -- a byproduct of the dramatic increase in the use of CT scans and X-ray guided procedures such as angioplasty. The benefit of these scans is not in question: Intense X-rays can reveal valuable information about injuries, diseases, and patients' response to treatment. Iodine-containing agents allow doctors to improve the scans even further, giving better "contrast" between the blood vessels and tissue, because X-rays are scattered differently by iodine. But as the iodine is carried by the blood to the kidneys, and filtered out into the urine, the iodine can upset the delicate balance that keeps the kidneys functioning. In recent years, manufacturers of contrast agents have begun to offer different formulations that may pose less risk to patients' kidneys. More expensive low-iodine and iodine-free agents are available to especially vulnerable patients, and to people who are allergic to iodine. But for everyone else, medical imaging specialists have tried to find ways to prevent the damage. N-acetylcysteine is already widely used to clear mucus in cystic fibrosis patients, and to treat overdoses of acetaminophen. It's also being studied for other uses. Tablets of prescription-strength N-acetylcysteine are inexpensive -- about 25 cents for a 500 milligram tablet -- and stocked by most pharmacies. It has few side effects. Over-the-counter supplement forms of the drug should not be used for pre-scan kidney protection. In addition to XXXXXXX and XXXXXXX the study's authors are XXXXXXX Dwamena, M.D., and XXXXXXX Cronin, M.B.B.Ch., both assistant professors of radiology, and XXXXXXX J. Bernstein, M.D., MPH, professor of internal medicine. The study was funded by the National Institutes of Health and the National Cancer Institute, and by Kelly's GE-Association of University Radiologists Radiology Research Academic Fellowship. None of the authors has financial connections with manufacturers of the drugs or contrast agents studied.
Follow-up: Will CAT scan damage my kidneys? 4 minutes later
Dr Bhabhe, Any insights in my below results? Thanks - XXXX BUN CREATININE eGFR XXXXXXX 2002 8 0.9 No reading XXXXXXX 2004 8 0.9 No reading XXXXXXX 2007 12 0.9 99 Dec., 2007 13 0.9 99 Feb., 2009 9 0.8 113 Oct., 2009 8 0.9 92 Nov, 2010 14 0.97 84 XXXXXXX 2011 14 0.95 86 Sept, 2012 17 0.92 89 Nov, 2013 13 1.01 88
Answered by Dr. Aditya Bhabhe 8 hours later
Brief Answer: SEE detailed answer Detailed Answer: Hi XXXXXXX I appreciate your concern. The study is done in 2008. Since then we have had multiple studies and reviews. Here is something which was published in 2012 and is an overview of all the studies: A CIN Consensus Working Panel agreed that CIN risk becomes clinically significant when the baseline SCr concentration is ≥1.3 mg/dL in men and ≥1.0 mg/dL (≥88.4 mmol/L) in women, mostly equivalent to an eGFR <60 mL/min/1.73 m2. Ref: A European Renal Best Practice (ERBP) position statement on the Kidney Disease Improving Global Outcomes (KDIGO) Clinical Practice Guidelines on Acute Kidney Injury: Part 1: definitions, conservative management and contrast-induced nephropathy. This was published in Dec 2012. This article states that if there is no diabetes, heart failure, dehydration etc then the risk of CIN is likely if GFR < 60. Your GFR is 88. So the risk is low. As you are worried you can have a discussion with your doctor about the following precautionary measures: 1) Use of low volume, non ionic contrast 2) Use NAC 3) Adequate hydration : most important as per the above guidelines 4) Avoid Nephrotoxic drugs (see nephrologist for this). As far as the drop in your GFR is concerned, the explanation is a little complicated. The equations used to calculate GFR are not very accurate if GFR is more than 60. So if we really want an exact number, we will require 24 hour urine creatinine clearance. Again a nephrologist will help you out with this. I hope this was helpful Regards Dr Bhabhe
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Follow-up: Will CAT scan damage my kidneys? 36 hours later
Dr. Bhabhe, Again, thanks for answering my questions. I saw in your last memo about consulting my nephrologist. My consultations have been with a urologist (my Dr.) so far - I haven't been assigned a nephrologist yet. Which is part of the reason I have posed my questions to you also. I will follow through with the CAT scan, with XXXXXXX I'll let you know the results. _______________________________________________________ Question: Hypothetical of course. If it turns out to be IGA nephritis, could the following scenario have taken place: History - I am HLAB27+. This was diagnosed in 1996, when I had a bout of UVeitis and the genetics reports came back positive. "I'm very lucky I haven't suffered any further attacks, or other associated inflammation diseases i.e. anklyosing spondolytis". Anyway back to my question. Two months ago when I had my urine sample taken and the lab found blood - I was also suffering from poison ivy on my legs (very bad), along with cuts on my legs from thorns. ( I was helping my father cut firewood). At the same time, I had given blood at the local American Red Cross. I was so dehyrdated that the left arm swelled, blood bruising was prevalent on one half of my forearm. The technician then tried my right arm, and though the need took, bruising also took place, again b/c I was dehydrated. (( Could the traumas of poison ivy, cuts on my legs and/or blood bruising in my forearms have created some kind of inflammatory response in my body, especially the kidneys ?))
Answered by Dr. Aditya Bhabhe 9 hours later
Brief Answer: Seems unlikely Detailed Answer: Hi XXXXXXX If you have IgA disease, it cannot be diagnosed on CAT scan. It can only be diagnosed by doing a kidney biopsy. IgA disease is an autoimmune condition. No correlation has been described between the disease and the various factors which you have mentioned. So its hard to correlate the two events. Regards Dr Bhabhe
Above answer was peer-reviewed by
Follow-up: Will CAT scan damage my kidneys? 24 hours later
Hi Dr. XXXXXXX Bhabhe, I rec'd your response. Thanks for letting me know. I'd rather have someone tell me that they don't know as opposed to someone who just guessed. If there's no science to back up the theory, then there's too much speculation. Bob
Answered by Dr. Aditya Bhabhe 9 hours later
Brief Answer: See detailed answer Detailed Answer: Glad I could be of help Dr BHabhe
Above answer was peer-reviewed by
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