this is a routine precautionary thing that quite frankly is NOT done often enough. it has to do with your kidneys try. if someones creatinine(the main indicator of overall kidney function)is actually out of range or is even in range but at the higher end,they wont use the contrast. they also check your potassium too for kind of the same reason? these both have alot to do with how that contrast would possibly effect the kidneys. contrast is just kind of harder on the kidneys, thats all. in normal people with normal kidney function, there really is not an issue so much, but if you actually have a kidney disease(i have liver AND kidney disease myself and decline the contrast as per my neph, even tho my labs are still within all norms)there can be some big problems with filtering it out which can lead in some cases to renal failure. i am kind of just doing in my case, the better safe than sorry route?
there is actually a way for people who do have kidney disease to take the contrast die safely. i did not find this out til i ended up with a brain aneruysm and HAD to have an angiogram(five in all) which uses ALOT more contrast than even an MRI would. its a med called "mucomyst"(acetylcistine(sp)). this is actually the antidote used in ERs when someone ODs on tylenol too. this really is an amazing med in what it can do for the contrast. it actually just encapsulates the contrast dye and safely removes it from the kidneys without it ever actually being filtered, so it does not (the contrast) affect them as it wouldd without using it. this was told to me by the radiology dept where i had my angios done and also had to use the muco when they coiled my aneurysm too. i had absolutely no changes at all in my kidney labs anytime i have had to have the contrast used. just some FYIs for ya if needed. the muco does smell rather heavily of sulpher(rotten eggs?) but for what it just does for my kidneys, well i manage to suck it down in some OJ.
i am sorry you are still looking for some answers here try,i know we have chatted before about your health problems. i really don't know what way they can actually use to try and tell if you would react to the contrast like you did the iodine. i know they always ask about whther or not you have an allergy to shellfish before giving it? i do think the base for the contrast used for at least the MRI is some form of squid ink type stuff, tho don't quote me on that. i just seem to recall that being mentioned to me when they had asked that question and i asked why?
i do hope this helped some. please let me know just what you find out hon. good luck, Marcia