Why is my TSH so low when my T4 T3 are so low?

[DizzyD]

Hi all can some please explain why my TSH is low despite my T4 T3 being low. Correct me if i have got it wrong but i have come to understand that TSH is released by the pituitary gland to stimulate release of more thyroid hormones if levlels are too low.

Since 1993 i dont have a thyroid so i am on levo but my pituitary gland should still release TSH.

I do have heart problems particularly afib which is under investigation. 18 April I had a stroke due to a clot caused by afib but thankfully i was successfully treated for clot. Presently my main concern is sorting out hypothyroidism because i am literally brain dead and so depressed.

Really would appreciate some help and advice

Here are my thyroid test results for 1 May 2024. Levo dosage prior to test was 75/50 alternate days along with 30 (half grain) of NDT daily.

TSH 0.351 0.27 - 4.21 = 2.1%

T4 16.0 12 - 22 = 40%

T3 3.3 3.1 - 6.8 = 5.4%

Please note, T3 is low because I did not take NDT after stroke 18 April. Depending on results of next retest I plan add a small dose of synthetic T3

Question is: Why is TSH so low?

thank you in advance.

[greygoose]

Correct me if i have got it wrong but i have come to understand that TSH is released by the pituitary gland to stimulate release of more thyroid hormones if levlels are too low.

If the pituitary is working correctly, yes. But pituitaries can work sub-optimally just like thyroids. It is a misconception by doctors that everyone has a perfectly functioning pituitary. They don't.

I do have heart problems particularly afib which is under investigation.

Your heart problems probably have more to do with your low FT3 than your low TSH. TSH has nothing to do with hearts. And low TSH does not cause heart attacks or strokes. Low T3 does.

[pennyannie]

Hello DizzyD :

Since there has been a medical intervention and you now do not have a thyroid -

your own natural thyroid function is compromised -

so it is essential to be dosed and monitored on your Free T3 and Free T4 readings -

and the TSH is not a reliable measure of anything once taking any form of thyroid hormone replacement :

I'd be inclined to slowly build up the NDT and wean off the T4 - Levothyroxine :

Looking back I think I saw you were / are on Amiodarone and this another reason why a TSH reading is not a reliable measure of anything - and why you need to ignore the TSH -

You need to be tracked on Free T3 and T4 readings with the aim being to get both these vital hormones within the ranges - and whether taking synthetic T3/T4 or NDT - aim for a Free T3 at least over 50% through it's range.

[DizzyD in reply to pennyannie]

Hi pennyannie thank you for reply. Sorry for late reply.Yes i stoppe amiodarone august last year due to it messing up my thyroid levels. Amiodarone via conversion pushed my levels over range so i stoppe taking it. Due to very long half life of this drug my levels have been all over the place ie going high and possibly triggering really bad afib (tachycardia).

I think amiodarone is out of my system now since stroke and thyroid levels are stabalised because only had two minor afib attacks (having 3rd afib attack today) since i had stroke but as greygoose mentioned low T3 can trigger afib and this could be the reason why i having the afib attacks.

My T3 results shown above really are low. Raised my levo dose to 75mcg daily after i received these results but stopped NDT. In all honesty i could have added T3 instead but i was afraid to do this because i suspected amiodarone (half life) still in my body was pushing T3 (via conversion) too high an triggering tachycardia type afib that i had when i was taking small amount of NDT.

Depending on results of next retest i will introduce some form of T3. Really would like to go with just NDT when the time is right. Not sure when this will be though because i am going through process (on waiting list) for mini maze procedure in sheffield to treat afib. Long story, but i dont think i need afib treatment (maze procedure) because severity of afib attacks was caused my heart medications which i should never have been prescribed to treat afib. Afib got much worse on medications. Top cardilogist said afib meds are a NO NO for me. The only mefication i take now is anti coagulant.

Sorry for lengthy post lovely. Really do appreciate your help and advice.

Have a rewarding day

Thank you