TSH 0.02 mIU/L on 100mg Levothyroxine - is this a problem?

[marbo]

Hi - my latest results are;

TSH 0.02 mIU/L (Range: 0.27 - 4.2)

Free T3 6 pmol/L (Range: 3.1 - 6.8)

Free Thyroxine X 16.9 pmol/l (Range: 12 - 22)

I am on 100mg of Levothyroxine and have hypopituitarism. I was aiming to try and get my T4 up to about 20pmol/l but at 16.9 my TSH has dropped very low to 0.02 mIU/L. Does this matter with hypopituitarism? Does very low TSH actually have any health impacts?

As I use more Levothyroxine i presume my body no longer produces TSH as all the T4 comes from the Levo?

The T3 is near the top of the range so would taking more T4 take it over?

Just wondering whether to stick to 100mg or go higher or if very low TSH is a problem then maybe cut back.

I have no symptoms at the moment of too much T4.

thanks for your help

[tattybogle]

One thing we know TSH does is to enhance the conversion of T4 to T3 in the cells ( via the deiodinases). it also has an effect on increasing the amount of T3 produced directly from the thyroid gland. However this certainly doesn't deem to be causing you any problem .... your fT3 is very good.

If TSH itself does anything else in the body i'm not sure we know what it is yet.

The commonly referred to risks of 'low TSH causing heart and bone problems', are from research looking at people with working pituitary glands , so this research does not really apply to someone who has a known pituitary insufficiency.... in their case you must look at the fT4 and fT3 levels directly to asses any risks , and dose .

Increasing Levo may or may not take your T3 over range .. you'd have to try it to see. but 100mcg is not a particularly big dose and many of us need slightly over 100mcg ... 112.5mcg and 125mcg are very common doses.

Taking more T4 when your already have a fairly good level doesn't always result in higher T3 , because if the body thinks it's got more T4 than it wants ,it will just convert more of it to reverseT3 ( rT3) which is inactive.

Since your fT4 is only mid range at 49%, and we know your pituitary doesn't work properly anyway .... If you don't feel well on 100mcg , then it seems perfectly reasonable to try increasing fT4 slightly to see what happens.

Since your fT3 is already pretty good, i'd go slowly ..... maybe try just 112.5mcg first.

ie 100mcg one day / 125mcg the next.

or split a 25mcg tablet in half to get 112.5mcg /day.

But .... don't just take more for the sake of 'numbers' if you find it doesn't actually improve how you feel. ... there are so many things we don't yet know ... there is recent science suggesting that the level of T4 (in everyone not just thyroid patients) is related somehow to the proliferation of cancer cells.... (more T4 =more proliferation ? ) ... so until more is known it would be unwise to say that taking your fT4 level higher than you need to doesn't matter at all. .. it might matter . or it might not .. we don't know yet.

[Crissy53 in reply to tattybogle]

My endo told me t3 or 4 really didn’t matter that much as when I took a natural thyroid Med my t4 was always off. Wen I switched to levo it now remains in the normal range…

[tattybogle in reply to Crissy53]

"My endo told me t3 or 4 really didn’t matter that much"

well they obviously do matter a great deal .. too much or too little of either /both are directly responsible for hyperthyroidism / hypothyroidism .. and not paying fT4 and fT3 any attention can obviously result in either overtreatment or undertreatment.

[marbo in reply to tattybogle]

Thanks for the information. I have looked into it and it seems high T4 may indeed be linked to increased risk of various cancers. Given this, should I actually lower my levothyroxine dose rather than aiming for 80% through range (about 20pmol/l)?Should I actually be aiming to be at around 14 pmol/l?I think 50-75mg would get to this level.

This might also raise my TSH slightly closer to range and my T3 is likely to be around 4.5.

thanks for your help

[tattybogle in reply to marbo]

depends .. i personally can't see much point lowering dose if doing so makes you feel less well.

All the other stuff is unknown /statistics/theoretical hints at risks/ seen in very recent research that may never affect us ..... but changing dose is definitely going to affect us.

It not as if the possible connection of T4 to cancer proliferation suddenly disappears at any point on the scale. If there is an issue, it's there for every human because every human has some T4, and plenty of them obviously have it at 'the top of the range' because that's how they decide what 'the range' is.

It's not about aiming for some theoretically safe numbers though is it .. it's about whether we feel well.

have you ever been on a lower dose ?

if so how did you feel on it ?

how do you feel on your current dose?

To me, this potential 'higher fT4 /more cancer?' question just means that some people who are using higher fT4 levels to get enough fT3 to feel well, might be better advised to take a little T3 instead rather than pushing T4 over range to feel well.

But reducing Levo and adding a little T3 instead is not a solution that is suitable or available for everyone.

[Localhero]

Hi marbo

I have no symptoms at the moment of too much T4.

But do you feel well at these levels? For me, that’s the real test. If so, I’d stay there.

Your FT3 is 78% through range and given that FT3 is the active hormone, that seems like pretty good going. But, again, how do you feel?

[marbo in reply to Localhero]

Generally I feel ok at the moment. I still have some fatigue but that seems to be getting better.