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CT with Contrast. Info Needed.

MikeK703's picture
Posts: 235
Joined: Sep 2010

My urologist had told me that the time would come when I would need a CT scan with contrast but I wasn’t expecting that time for another six months. My GP is suggesting a CT scan with contrast for an issue not necessarily related to my kidney cancer. He has advised me of the risks to my remaining kidney, risks I was already aware of. He tells me that he spoke with a radiologist who said that contrast is not dangerous to the kidney if the kidney is “normal.” Normal being defined as a GFR over 60. He wants me to have another blood test to see if, hopefully, the GFR has gone up since my last one just a few weeks ago. I don’t have a lot of hope for that since my last reading was 56 and prior to that it had fluctuated for the last 19 months between 47 and 56. He will be consulting with my urologist and nephrologist next week and is expecting a decision from me. I think I have no choice but to do it, but there are a few things I need to have straight in my mind before I make that decision.
1. Has anyone who has had a radical nephrectomy had his/her GFR readings return to what they were before surgery? I am thinking that generally speaking the younger folks might say yes to this and the older folks might say no. It would be very helpful to know that an older person had his/her readings go back to normal.
2. If your GFR readings declined after a radical nephrectomy and did NOT go back to normal, how big of a drop was there in the readings? Mine started out over 90 and is now 56. Anybody have similar results?
3. Has anyone who has had a CT with contrast since their radical nephrectomy noticed that their GFR readings went down temporarily or permanently and can attribute that drop to the contrast?
Thanks for any info you can provide.

icemantoo's picture
Posts: 3351
Joined: Jan 2010


My understanding of the question of contrast is a little different than yours and may be outdated since I have not had a Contrast CT for about 3 or 4 years.
First the Contrast can damage Kidneys. Before every Contrast CT I had a script for blood work to measure my BUN and Creatine no's and their ratio. Unless the ratio was a certain number or higher or lower, I don't remember which I could not have the contrast. They did not use GFR numbers then, but may now. Next from experience on these things I trust my Urologist and Nephrologist to interpret my numbers as the GP is only giving you his version of what somebody told him. Next the Radiologist should personnally be aware of what your current blood work shows AND the fact that you have only one kidney so thst if there is a concern about the contrast, he can discuss it with your Urolgist or Nephrologist. I hope this helps. Having contrast when there is a problem can and does cause Kidney failure.


MikeK703's picture
Posts: 235
Joined: Sep 2010

Thanks, Iceman. My GP didn't mention BUN, only GFR, but he is planning to take another round of blood tests before the CT and I imagine BUN will be one of them. My BUN reading has always been in the standard range so I guess the important number is going to be the creatinine and the ratio will decide whether or not I can undergo the scan. The only "problem" the GP mentioned was my GFR, saying that above 60 was normal and below 60 was not. He has already spoken with the radiologist and will speak with the urologist and nephrologist next week. I will make it a point to speak with those two myself so I understand this better. Since my urologist told me I would eventually have to have a CT scan with contrast, I guess there is not much difference if I have it 6 months earlier than expected, as long as the blood work numbers are okay, and I'll make sure I hear directly from the kidney guys before saying yes. Do I understand you correctly, though, that you had CT scans with contrast done in the past and they did not negatively affect your remaining kidney? I recall you saying you were in Stage 3 CKD. Were you in Stage 2 when you had the scans?
Thanks again,

Texas_wedge's picture
Posts: 2798
Joined: Nov 2011

Mike, i strongly suggest you go here:


which should tell you everything you need to know on the subject (plus a great deal you don't as well).
It seems mandatory for the radiologists to have a whole battery of emergency meds and gear available in case there is an adverse reaction to the contrast!! I made a few remarks a little while ago about the possible delayed effects and the resultant dangers, after Rae had mentioned having an uncomfortable reaction.

This info. is somewhat reassuring:

"Key point: Contrast nephropathy is uncommon and usually transient. A critical diagnostic study should NOT be delayed because of excessive concern regarding possible contrast nephropathy. Strategies to prevent nephropathy in patients with renal impairment include hydration, reduction of contrast dose, hydration, sodium bicarbonate infusion and discontinuation of nephrotoxic drugs."

Texas_wedge's picture
Posts: 2798
Joined: Nov 2011


You may want to read the thread "feeling sick after contrast/ct scan" where Rae mentioned her reaction. The excellent ucsf site I referred to above goes seriously wrong I believe on one pretty important point. They say this:

"Most major and minor reactions will occur in patients without any known risk factors. Virtually all life-threatening reactions occur immediately or within 20 minutes after contrast injection."

While that is no doubt accurate, it is in danger of implying that after about 20 minutes you can stop worrying about possible adverse effects. This is not advisable. See, for instance, this from the Univ. of Wisconsin:

"Delayed Contrast Reactions
Delayed contrast reactions can occur anywhere from 3 hours to 7 days following the administration of contrast. Since patients are generally discharged from the radiology department within 30 minutes of contrast administration, these reactions are rarely observed by the radiologist supervising the contrast administration. These events are often not brought to the attention of the radiologist since the delayed event may not be ascribed to the contrast media and these evens are often self limited. Regardless, it is important for anyone administering intravenous contrast media to be aware of delayed reactions."

This is in an interesting tutorial for the pros in the field and comes from the U. of Wisconsin. I don't know about nausea and headache but for cutaneous reactions they do say:

"Delayed cutaneous reactions are more common in patients who have had a previous contrast reaction .... While the exact mechanism of the delayed reaction is unknown, they can recur if the same contrast medium is administered again."

As against the uncertainty about the mechanism, contrast this:

"It has long been recognized that anxiety plays a role in evoking and potentiating contrast reactions. Therefore, your behavior and conduct become important factors in your ability to successfully manage the patient. You must maintain and display an unruffled, orderly, deliberate, capable, and effective demeanor, one that elicits confidence and promotes a sense of well-being in the patient. These same qualities are also important in coordinating the activities of staff members assisting you. You must be able to take charge, assign tasks, monitor activities, reassess the patient, and make effective decisions as circumstances change.
Those assisting should execute their duties quietly, minimizing anxiety-provoking conversation."

The ucsf advice is qualified with the following caveat:

"In general, these guidelines are simply guidelines, and slavish adherence in every case is neither expected nor appropriate. Physician discretion and judgment are paramount, and commonsense should be applied to individual patient circumstances. For example, creatinine testing can be omitted for an urgent study where time is critical, particularly a contrast-enhanced stroke CT protocol requested by the Emergency Department (this determination should be made by the requesting physician). Conversely, it may be prudent to check creatinine in a sick debilitated patient even if they do not have any of the specific factors listed above."

For what it's worth, on a personal note, I've now had 2 CTs with contrast and will probably have them every 3 months from now. My eGFR recently (path report before 2nd scan) was 53. They aren't taking too much account of this or my age, not too bothered by the radiation aspect or the contrast but maybe that's because at pT4 stage 4 grade 4 they're not expecting me to live long enough for these factors to make any material difference?

MikeK703's picture
Posts: 235
Joined: Sep 2010

Thanks again, Tex.
Our posts crossed. I think everyone here appreciates the major efforts you make to answer questions. And thanks for mentioning your personal experience. I guess the question we have to ask ourselves is, "Is the benefit worth the risk." As soon as I get the scoop on the risk from the neprhologist and urologist and the benefit from the other doctors involved, I can decide. The problems never seem to end.

keephopealive11's picture
Posts: 21
Joined: Dec 2011

I am 48, and had the right kidney removed on Jan 24. The creatinine was 1.4 on Jan 26. Had another blood test on March 16. It was 1.34 (eGFR 62). Wondering how to improve it before the next CT. Will diet help?

MikeK703's picture
Posts: 235
Joined: Sep 2010

As Jon can testify (see his posting above), the GFR can improve. The first thing you have going for you is your age. Unless you have kidney disease, often caused by diabetes or hypertension, the younger you are, the easier it is for your GFR to bounce back after surgery. At least this is my understanding of it. John is older than you so that bodes well for you. I've been told that at my age (64), and history of hypertension, the likelihood of GFR improving much is not so good. The best I can hope for is that it stabilizes, and 19 months after surgery, it has done just that. As far as diet goes, I was first told by my urologist I should be careful not to go on a high protein diet. Later, my nephrologist said that this kind of warning is primarily for folks in the later stages of chronic kidney disease. I still follow the don't-overdo-the protein-rule simply because I was never a big meat eater anyway. If you're a cola drinker, switch to an uncola or cut way back because Coke and other colas contain phosphorus, too much of which is not good for the kidney. Keep away from the NSAID type of over the counter pain medications like ibuprofin (Tylenol is usually recommended for folks with just one kidney). And drink plenty of water to keep hydrated, as dehydration can increase your creatinine level (thus decreasing your GFR).
Hope I got everything.
Good luck,

Posts: 67
Joined: Sep 2010

What is a GFR. Every time I get blood work before my CT scans, I get a creatin but no Bun/creatinine reation since it is normal and some other blood tests, but not the one you are talking about. Is that standard. My urologists never have ordered that test?

Texas_wedge's picture
Posts: 2798
Joined: Nov 2011

It stands for Glomerular Filtration Rate and is usually stated as eGFR, where e means estimated from the test results. It's a measure of how well your kidney(s) is/are functioning.

You'll find a nice short and simple explanation here (copy and paste this link into the white address bar near the top left of the window in your browser)


At the age of most kidney cancer patients, the figure is very likely to be below 60 even if they don't have 'kidney disease' - the term 'chronic kidney cancer' is used quite loosely in this way but it does mean that if you're much below 60 you need to treat your kidneys with respect.

garym's picture
Posts: 1651
Joined: Nov 2009

I think you meant chronic kidney disease or CKD did you not?

Texas_wedge's picture
Posts: 2798
Joined: Nov 2011

Indeed I did - thanks for correcting the slip Gary, which just shows I'm not firing on all cylinders.

Posts: 9
Joined: Jan 2010

This is late in the thread but if someone is reading this in the future it might help:


February 19, 2008
Before a CT scan or angiogram, many people should take inexpensive drug to protect kidneys, U-M study finds
Iodine contrast agents that enhance the scans can harm vulnerable kidneys, but N-acetylcysteine taken beforehand can protect at-risk patients

Ann Arbor, MI – 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.

This top-down view of a patient's abdomen was made using one of U-M's advanced CT scanners and an iodine-containing contrast dye that reflects the CT scanner's X-rays and improves the visibility of certain details. The kidneys are the two gray heart-shaped areas on either side of the spine, which is bright white. Because of the contrast dye, the medulla (inner) part of each kidney can be distinguished from the cortex (outer) part -- a level of detail that can be important in diagnosing disease. But since CT contrast dye can also harm the kidneys of some patients, U-M researchers say many people should receive a drug called N-acetylcysteine before their scans, to protect against such 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 Aine Kelly, 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 senior author Ruth Carlos, 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 Kelly. “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.

Kelly, Carlos 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, Kelly 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 Kelly and Carlos, the study’s authors are Ben Dwamena, M.D., and Paul Cronin, M.B.B.Ch., both assistant professors of radiology, and Steven 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.

Reference: Annals of Internal Medicine, 19 February 2008, Volume 148 Issue 4
Written by: Kara Gavin

Wolflvr's picture
Posts: 14
Joined: Dec 2012

Hmmm... Every single CT I have had has been with and then without contrast. I've always had bloodwork until the last one in November. I was expecting bloodwork beforehand, but none had been ordered and no one seemed the least bit concerned (though I asked everyone - repeatedly). My kidney function has been "excellent" from day one. After the radical nephrectomy the doctors continued to be "amazed by" my kidney function and how it "never skipped a beat". I assumed they were continuing to monitor bloodwork due to my anemia which is fairly severe and has been since I was 16, although it seems to have improved quite a bit since the surgery. I had no idea contrast CT could cause kidney damage and feel pretty foolish since I'm a research addict and yet never thought to research those. I see my nephrologist again January 2nd and my Urologist for another round of scans in February. Should I ask my Nephrologist about this?

todd121's picture
Posts: 1449
Joined: Dec 2012

I'm pretty new to this site. I just had my kidney removed last week. I did have a CT scan with contrast before they did the procedure.

I have a feeling they'll be doing regular scans, and now that I have only one kidney I'm concerned about the contrast.

Why wouldn't they do an MRI instead of a CT scan with contrast if the contrast has risks? I never understood why my doc did the CT scan with contrast if an MRI would have given the information he needed. Do you think it was cost? I know they had CT machine right there nearby and not sure they had an MRI machine.

Texas_wedge's picture
Posts: 2798
Joined: Nov 2011

todd, they may not have an MRI machine, may not have had an early time slot, the procedure is a lot more expensive and, most importantly, for your present purposes it will probably give inferior information to that on the CT. The most recent technology involves less radiation and the contrast dyes have been improved to a point where, with sensible management, the risks are well worth it when compared with not getting the information you discover from it.

Posts: 1
Joined: Apr 2013

Hi, I had a Radical Nephrectomy of my transplanted kidney aged 31. Immediately prior to my Nephrectomy, my eGFR in my soon to be only kidney was 38. Despite an episode of Septic Shock 6 months later, requiring admission to Intensive Care, during which my eGRF dropped to 21, it peaked shortly afterwards at 56 (this compensatory increase was expected within 18 months of surgery)


Due to other Renal & Urology issues (recurrent infection, Haematuria, sudden onset Hypertension) I have since had 5 Contrast CT scans (chest, abdomen, pelvis, head, Cardiothoracic Angiography etc.) Prior to the scans, my eGFR had dropped to a fairly consistent level of 44, and remained pretty much unaltered immediately following the scans, and in the months that followed. This week, I had a CT scan with Contrast, and after 24hrs of I.V fluids, my eGFR increased to 59, which is actually the highest it has ever been.

Both myself & various care providers had valid concerns about the Nephrotoxic effects of the amount of Contrast Medium I have had since the onset of my illness in 2002, but I seem to have escaped unharmed in terms of the function of my solitary kidney, which is surprising, especially given  how high my Blood Pressure is, the number of UTI/Pyelonephritis infections I've had, in addition to huge quantities of Gentamicin, Opiates, N.S.A.I.Ds & General Anaesthetics, Sedation & reversal.

I hope this information is helpful,



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