I commiserate with you, and I am so sorry that you have limitations for being able to obtain help. How utterly frustrating!

To answer the question about the MRI dye and kidneys:
I've had countless MRIs over the past 10 -14 years, several of them with dye contrast, for the same reason that you have: demyelination of brain matter of unknown etiology. Each time I was informed to drink LOTS of water to flush out the kidneys. Thus far, I have no evidence of kidney damage other than benign cysts. All blood tests show normal kidney function. I did have at least two cases of kidney infections in my mid-adult years. This Wednesday, I'll be having an ultrasound of right kidney to rule out stones or anomalies since I've had right flank pain. but that could also be due to serious issues with my lumbar spine and hip joint. I hope to find possible answers to my seemingly endless situations.

AS FOR THE DEMYELINATION: First discovered back in 2014, following symptoms that alarmingly indicated MS. I'll skip all the in-between info (I’ve delineated them in other posts within this site), but indeed I had the "classic" signs: upsetting double vision, "suspicious" left optic nerve (which an MRI later revealed 4th nerve palsy), confusion, memory issues, nerve zaps within my cranium and down the spine, facial nerve issues, fatigue, etc., inability to walk without a staggered gait, miserably failing balance testing by neurologists, and a few other concerning symptoms/issues. MRIs also revealed TIAs (Transient Ischemic Attacks). Was seen by countless "specialists" from prestigious teaching and research hospitals in NYC, and bottom line was that I had to have a yearly brain MRI to keep track of any new white matter formation. White matter "stabilized" and stopped about 3 yrs ago, but the yearly MRIs continued without contrast. I will be having another soon. A previous one ('22) showed "small but concerning changes" and I'll be addressing that with my new neurologist. I say "new" because I dismissed the neurologist that I'd been seeing since he failed to say anything about the radiologist's findings, simply had said "no changes"...and his dismissiveness is not something that anyone with demyelinating disorder wants to or should have to deal with. He also refused to write the script for the MRI in 2023, so I am way overdue for one. (I demanded a copy of the '22 radiologist's report and learned about the "small changes" after a couple of years of NO new white matter, and my primary confirmed it during a visit a few months later.) I've had disturbing symptoms that need to be addressed and will be doing so with the outstanding neurologist from a different medical practice. He has been taking care of my CRPS (chronic regional pain syndrome) which he diagnosed last year, as well as nerve damage of left leg, and is highly regarded within his field, along with 30+ years of experience.
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To address what another mayo.connect member said: Yes, from researching, white matter can result from several sources, including long-term high cholesterol and even Lyme disease (which I had three times years ago). But I personally would not say "don't worry about it". Rather, allay your concerns and fears by having at least one more followup MRI to compare and see if any new formations are detected. DEFINITELY seek out a neurologist, preferably one with experience in this specific area. Let him/her determine "what is/isn't" reason for concern, and an action plan. Obtain and keep copies of your tests/procedures, MRIs and radiologists’ reports. I have ALL of mine, including blood tests/results. Journal any new symptoms, no matter how simple or insignificant they may seem.

It is possible that age may enter into the equation (I was about 62 when "symptoms, conditions" first emerged, and will be 76 this coming August). Brain MRIs can also reveal other issues/changes such as TIAs, shrinkage, etc. So, yes, I would advise you NOT to ignore the demyelination. For me, "out of sight, out of mind" is not an option since I STILL have balance and gait issues (actually has gotten worse, so much so that it has affected my self-esteem and mental health, and I detest being out in public unless I'm holding onto a cart; canes are valueless). I've had other more recent "developments" that have contributed to my proverbial plate, but I advocate for myself, and I'm fortunate and grateful to have wonderful medical insurance and the ability to seek professionals without needing approvals or referrals.

Hang in there, and do see if there are support groups, etc., that can help you. Possibly a center for the aging? Within Medicare itself? A research/teaching hospital?

I hope you can find answers that will alleviate your concerns/fears because I know exactly what you are experiencing. I’ll pray that you find successful avenues.🙏🏽🌺