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Hashimoto's encephalitis - has anyone heard of this?

Thanks everyone for the help. So appreciated. I posted earlier about the mental decline and general cognitive problems I am experiencing. Does anyone know of a condition that is called Hashimoto's encephalitis? Apparently it is caused by the same antibodies that attack the thryoid but they attack the brain. I read that it is treated with prednisone. Does anyone have any thoughts on this? Could it be a possible cause of the problems I am having.

13 Replies

Also known as steroid responsive encephalopathy.

Some suggest that this occurs when there are antibodies in the cerebrospinal fluid (CSF) (not sure if only thyroid peroxidase antibodies were checked - or thyroglobulin as well).

Quite a number of accounts are available just by searching.

This (very USA) page is a useful starting point for more information:



You might want to look at previous posts on Hashimoto's encephalopathy



Sorry to hear you feel so unwell. I suffered massive cognitive problems and considered Hashimoto's Encephalitis whilst medicating T4 mono-therapy as had the seizures and light flashes in my head. I now medicate NDT and although feel well most of the time, horrid symptoms still return if I get over tired//emotional//run down.

NDT (like all thyroid meds) will only work well if fundamentals are in place and the ratio of T4:T3 (in NDT) doesn’t suit everybody. You have over-range T3 results on 12 hours of fasting when taking no meds, so I would say you are overmedicated and taking too much thyroid hormone replacement can be counterproductive. Also test results have their place but remember it is not the amount of thyroid hormone sloshing about in your blood stream but the amount that is actually working on an intracellular level.

FT4 is usually lower when medicating NDT and you have high T3 levels but if they aren’t able to cross the cellular membrane in order to have biological activity and work their magic, you will suffer hypothyroid symptoms. Thyroid receptor site defects can be caused by elevations in cortisol or homocysteine. (see below).

Thyroid hormones transport into the cell is energy dependent. Therefore, any condition associated with reduced production of the cellular energy (mitochondrial dysfunction) such as diabetes, obesity, anxiety, depression, fibromyalgia, physiologic stress and anxiety, inflammation and chronic illness, high cholesterol and triglyceride levels, blah, blah, blah ... (in fact everything associated with hypothyroidism.. ) .. will also be associated with reduced transportation of thyroid hormone into the cell, (whether medicated or not) despite normal (or elevated as in your case) thyroid hormone blood results.

If NDT is not “right” for someone, it can initiate a Hashi attack which may be why you have a tennis ball in your throat which is sore and your voice is low and hoarse. If your thyroid antibodies are elevated (putting your immune system into a state of high alert), if may be that the amount of NDT required to suppress the Hashi attack, exceeds that of the hormone amount actually required for replacement. In this instance you would need to reduce thyroid antibodies and a great book in understanding all of this is “The Root Cause” by Isabella Wentz.

Another reason why NDT is often not tolerated is nutrient and iron deficiencies and cortisol elevations or deficiencies. Iron is key for conversion of T4-T3 and low levels may also decrease deiodinase activity resulting in conversion to reverse T3 (rather than the active hormone). Although you have high T3 levels, this could be from over medicating and be unusable if RT3 were to be elevated.

A deficiency in Vit B12 is common in hypothyroidism and known to cause possible neurological concerns. Also Folate (B9) works with vitamin B12 to help create, develop and regenerate red blood cells and make iron work properly. It participates in the homocysteine metabolic cycle and adequate levels are required to keep this amino acid in check as high levels are considered a significant risk factor in disrupting thyroid metabolism (& also cardiovascular disease ),.

Sufficient cortisol levels are required for someone to tolerate thyroid hormone or may interfere with the HPA axis which in turn suppresses thyroid function and weakens the immune system, as is needed to receive T3 from the blood into the cells where it becomes active. Inadequate cortisol levels causes so many imbalances in other hormones, all of which are (indirectly) required for good thyroid hormone synthesis.

Reducing your NDT will help in lowering over range T3 levels and you may need to add a little T4 (Levo) to balance, and most importantly address all nutrient deficiencies. Thyroid hormones should be rested six weeks after meds dose adjustment. Because of the T3's (within NDT) rapidity of onset achieving a fast peak serum concentration, I found it useful in medicating doses split into three until T3 tolerance improved. Once adrenal health improved, I was able to reduce to multi dosing twice a day and still continue to do this.

You previously say your iron levels are low. Are you supplementing and if so with Vit C, which will aid absorption and help avoid constipation ? ? .... Have you had Vit B12, folate and Vit D tested ? ? … . My thyroid meds only work with optimal levels of everything and sups can bind to thyroid hormones making them unusable so take any two-four hours away from thyroid meds.

If things still weren't too improve after rectifying deficiencies above, you could look into sex hormones as elevated T3 can alter the balance resulting in elevated SBHG, which attracts free T3, also disabling it from entering the cells.


Wow radd! You deserve a standing ovation for this reply 🙌🙌🙌


Dear Radd

Thank you so much for your detailed and thoughtful response. Words cannot describe my appreciation. Thank you.


It is quite rare! I also thought I had this when first diagnosed, but in fact brain fog and memory problems are very common in just plain old Hashimoto's and hypothyroidism. have you optimized your b12, vit d, folate and ferritin? And how are you thyroid blood results? Cognitive functions are common with under medication.

I thought I was doomed with my memory problems but when I'm on the right dose I don't experience it anymore.


My Mum has HE/SREAT neurologist said he would probably only see one case in his career.

It's a very, very, very hard diagnosis to get. Whilst my mum was symptomatic she would have been unable to write the post you have.

I would persue other mediators/causes for any cognitive decline first before considering HE.

Best wishes.


Thanks Kes. I needed to hear that. Thank you.


Just to add having read your other posts is that when my Mum got her diagnosis her TPO antibodies were "The highest the lab had ever seen."

So if you are worried have you TPO antibodies checked.

With the caveat that like hashimotos thyroiditis levels of antibodies do not necessarily correlate with how bad the condition is or how symptomatic a person is.


Hi Kes8, do you remember what the TPO reading was? The the doctor mention a correlation between TPO count and the possibility to develop HE? I ask because my antibodies are rather high


Unfortunately I don't have the exact figure just know it was extraordinarily high.

What we did learn at the time was the exact figure doesn't matter.

Potentially you could have one hundred times the amount Mum had but it just so happens that her brain was sensitive to the antibodies and hopefully your brain is not.

I don't believe that unless mum had had seizures and weeks of very severe symptoms (hand tremor, seizures, confusion, agitation, dementia, left-side hemiparesis, stroke-like episodes, aphasia, hallucinations and more) then diagnosis would not have been made. They tested the TPOs because we insisted and there wasn't much else left to test.

I have Hashimotos thyroiditis and understand the brain fog etc. and have to really, really stress it is nothing like the severity of HE.

Just to reiterate HE although believed to be under-diagnosed/reported is very, very, very rare.


Thanks for the information Kes8 I really appreciate it. Good to know that the numbers don't necessarily pre-dispose someone to getting HE, I know I don't have it since brain fog does disappear when I'm optimally medicated, but just wanted to be know as my antibodies are over 1000 (when the range ended at 1000 so I actually don't know how high they are). Really sorry to hear that your mom went through such turmoil, I can't imagine what it must have been like for her and yourself.


Hi, I have severe cognitive issues and was checked out for this condition by an enthusiastic neuro. But my understanding from the literature is that it is very rare and completely debilitating often to the point of stroke/seizure/coma symptoms. Here is a link to the Encephalitis Society with an overview

I was offered high dose intravenous steroids as an inpatient but asked for a 2nd opinion. Steroids can be life saving in the right situation but also carry huge side effects and a previous dose of them for something else left me in a wheelchair for a while.


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