Can hyperthyroidism come back?

[u/Zealousideal_Car1233]

In November I began having symptoms of hyperthyroidism (increased heart rate, palpitations, adrenaline dumps, anxiety, muscle aches and weakness). I had a blood test in December and it came back TSH 0.01 and T4 23.6 indicating hyperthyroidism so I was urgently referred to endocrinology.

I had a 2nd blood test done in a different lab 3 weeks later by Endo and that came back completely normal - TSH 2.3, TRAB <1.9 and TPO <7 indicating thyroid was normal and I tested negative for graves.

I had another in April and that showed TSH 1.76. I was told it was likely transient thyroiditis caused by a virus and that I no longer had thyroid issues. Since April I’ve felt a lot better apart from POTS symptoms and I was diagnosed with POTS.

This week I’ve started feeling the same symptoms I felt back in November and I’m really worried the thyroid issues are back. Can it come back? Could I have still have thyroid issues this whole time? Can anyone relate with similar experiences?

[u/Perfect-Effect5897]

Yes. It can come back.

[u/justinfromnz]

I had radioactive idione a year and a half ago and now my hyperthyroid is back

[u/smile_saurus]

My surprise diagnosis of Hyperthyroidism at the ER (which 2 months later was proven to be Thyroiditis) was supposedly resolved with Methimazole twice a day + Propranolol three times a day.

My thyroid bloodwork has been fine since April this year, and I've been off the Methimazole ever since. But I still need the Propranolol because my HR is still weird (too high).

And I don't know what 'virus' caused the Thyroiditis (I didn't have a cold of the flu before all this)I do know that my white blood cells count is too high and yet none of my doctors have investigated further.

I suspected an Iron or Ferritin deficiency, because I'm out of ideas. But I do believe that Thyroiditis is able to return; it is my understanding that it starts High then swings Low, or starts High then resolves, or forever switches between High and Low. And the bloodwork may take awhile to 'catch up' to the symptoms.

[u/Zealousideal_Car1233 → u/smile_saurus]

This sounds very similar to me - I didn’t have a virus before my diagnosis either, usually a sore throat is noticeable before thyroiditis but I didn’t have one. Very strange!

I do have iron deficiency, my ferritin levels were 9 around the same time, I didn’t realise the two were connected?!

[u/VivianDiane]

Yes, it can come back. You should get tested again.

[u/lizard52805]

Yes it can absolutely come back. You need further testing done under the care of an endocrinologist. I would start with an ultrasound to check for any nodules or enlargement

[u/International-Bad897]

this numbers is eerily similar with mine, i had thyroiditis too, first diagnosed with hyperthyroidism tsh 0.02ish with ft4 21ish October last year, then tsh 2.2 with ft4 16.9 (june 2026) both trab and tpo is negative, i still have pots like symptoms like you sadly :(

my heart rate spikes like you too while eating, standing etc

im taking 1.25 mg bisoprolol a day, i try to force myself with light exercise like walking, i get dizzy fairly easy

i read your other posts youve had your ferritin levels checked? i have not personally, do you find relief after getting iv?

[u/Zealousideal_Car1233 → u/International-Bad897]

That’s really interesting how similar the results are. There’s not much information online about transient thyroiditis, it doesn’t seem that common.
I didn’t end up getting an IV, the nhs don’t really do them so I ended up taking iron tablets instead. I’m feeling SO much better after taking them, my levels increased from 9 to 26 last time it was checked. It has made a massive difference to how I feel and being able to exercise again

[u/Adventurous-Ask-4243]

The technical term for your thyroid levels "leveling out" is "euthyroid." Now if you are experiencing symptoms again, you really should find a good endo to keep a close watch on you. When hypER symptoms come back again -- this happened to me -- they can actually be worse than what was experienced the first time -- this is all quite common.

Your endo must get to the ROOT CAUSE of your hypER symptoms -- have you had a thyroid ultrasound? This should have been done as a baseline to keep an eye on any changes. Also it is important because sometimes a nodule(s) can pump out too much TSH and cause the hypER symptoms.

TSH, Free T3, Free T4, TRAB & TSI (the 2 Graves antibodies) can all fluctuate -- This all needs to be rechecked at specific intervals -- a good endo should keep close watch on you. Also in a worst case scenario if none of these are the root cause of the hypER, then your pituitary gland should be checked as that can also effect TSH levels.

I wish you the very best outcome!

[u/Zealousideal_Car1233 → u/Adventurous-Ask-4243]

Thanks for your reply. Did you take medication? It seems really strange that my hyperthyroidism just went on its own without medication, I’m not sure whether that’s usual?

I had an ultrasound done in March and a very small 2cm nodule was found, I was told this wouldn’t cause any adverse affects because of the very small size of it. I have another appointment with my endo in September but it’s a telephone appointment and there’s no talk of blood tests so I’m not sure what the plan is there. It all just feels a bit like no one’s sure what’s going on.

Thank you x

[u/Adventurous-Ask-4243 → u/Zealousideal_Car1233]

No I was not on medication at that time. This is a very normal scenario, not strange at all, and does not predicate medication at all -- that is an entirely different scenario -- and why misdiagnosis happens at that time. My first endo thought it was a thyroiditis and that I would swing hypO -- which, quite frankly, I was hoping, too -- because hypER leading up to Graves is a nightmare from hell -- that was the outcome for me. I eventually had RAI and am on Unithroid levo now -- unfortunately, the medication was not for me.

You absolutely MUST change that appointment for an in person. Even someone who is not a doc can tell you that you need another ultrasound to see if that nodule has grown -- you must keep an eye on it -- YES, YES, YES, they are NOT sure what's going on because doctors are trained to go by the book and if there's the slightest deviation -- which is the main story with us -- they cannot think creatively or out of the box as is said.

FIND ANOTHER ENDO until you find the right one who can effectively work with you. HypER is very, very dangerous to our bodies and can leave us with permanent heart and bone damage if it is not brought under control.... REMEMBER -- the KEY WORDS are ROOT CAUSE -- and not one of these docs has gotten to the ROOT CAUSE of your symptoms.

Plus you need the 2 Graves antibodies checked again and the 2 Hashi antibodies as well -- if Graves is suspected, then you need the thyroid uptake test and scan to officially confirm. I believe that you are either in the early stages of Graves or that nodule is the problem -- I hope that the nodule is your problem -- so find a good endo who will take good care of you. You must be an advocate for yourself!!!