My need for levothyroxine is decreasing..

[Greeneyes14]

In a nut shell:

June 2021- diagnosed with hypothyroidism, TSH 100+, commenced on levothyroxine. Antibodies suggest hasimotos.

Fell pregnant Dec 2022- increased levothyroxine as per guidelines. Post pregnancy, returned to regular dose 125mcg.

Fell pregnant again Feb 2024, increased levo to 150mcg, towards end of pregnancy my T4 was elevated and TSH suppressed so advised to reduce dose to 125mcg.

Post pregnancy blood check, again T4 high, TSH suppressed. Advised to drop to 100mcg, plan for repeat 6-8 weeks bloods.

I have just had my bloods taken again, my is currently T4 19.7, TSH 0.149. I have been advised to reduce my levo to 75mcg, I asked my Doctor why this may be, as he was perplexed my need for levothyroxine has reduced lower than pre pregnancy, and has no answer as to why this is happening.

Since reducing my dose, I have found I am gaining weight, despite no real change in my diet/exercise (though I am 12 weeks postportam), and also increasingly tired (despite getting much more sleep than earlier post pregnancy period.)

Anybody have any suggestions why my body ha suddenly decided it doesn't need as much levo?

[Jaydee1507 Administrator]

Are you testing as recommended here?

Do you do tests as per the protocol recommended here? Recommended blood test protocol: Test at 9am (or as close as possible), fasting, last levo dose 24hrs before the blood draw & no biotin containing supplements for 3-7 days (Biotin can interfere with thyroid blood results as it is used in the testing process).

Testing like this gives consistency in your results and will show stable blood levels of hormone and highest TSH which varies throughout the day. Taking Levo/T3 just prior to blood draw can show a falsely elevated result and your GP/Endo might change your dose incorrectly as a result.

Good profile. Have you continued to maintain key vitamin levels at optimal and what supplements are you taking now? When did you last test vitamins?

Sometimes low vitamin levels can affect TSH.

[SlowDragon Administrator]

ESSENTIAL to get FULL iron panel including ferritin

Did you have heavy blood loss during labour?

Also Vitamin D, folate and B12 need testing too

For GOOD conversion of Ft4 (levothyroxine) to Ft3 (active hormone) we must have good vitamin levels

Low vitamin levels will result in lower TSH, higher Ft4 BUT low Ft3

Low Ft3 will result in ongoing hypo symptoms

What vitamin supplements are you taking

When were vitamin levels last tested

[Jazzw]

I’m not so sure that your body has decided it needs less levothyroxine. I think you have a doctor who is (a) overreacting to a low TSH because they don’t understand how the hypothalamus-pituitary feedback loop works and (b) doesn’t understand how autoimmune thyroiditis can flare and go back into remission.

What was the laboratory reference range for your FT4? Did your doctor do an FT3 test before deciding to reduce your levothyroxine dosage? Did your doctor mention the possibility that your thyroid may currently be being attacked by the autoimmune disease, which in turn can make it (temporarily) put out a bit more thyroid hormone than it normally does? Childbirth quite often causes this (that’s why so many new Mums discover they have a thyroid condition shortly after giving birth).

[greygoose]

I would say, it's probably down to you having Hashi's.

As you probably know, Hashi's is an autoimmune disease where the immune system periodically attacks the thyroid and destroys it bit by bit. During an attack, the dying cells leak their store of hormone into the blood, causing levels to rise - maybe just slightly, maybe a lot, depending on how much hormone those cells were stocking. So, your increase in FT4 is very likely due to an attack on your thyroid and is only temporary. If it is what we call a Hashi's 'hyper' swing (although your levels aren't hyper) the level will eventually go down again and you will need your full dose of levo.

Probably/possibly the reason you've put on weight and have other hypo symptoms is that the cells destroyed were only stocking T4, so your FT3 didn't budge. But now you've reduced your levo, your FT3 has dropped too, and it's T3 that causes symptoms, not so much the T4.

Or, it could just be that your conversion has got worse, so the FT4 level has risen because it's not being used.

These are just theories based on the information we have. But it can't be proved unless the FT3 is also tested along with antibodies.