A little bit baffled why T3 has reduced slightl... - Thyroid UK

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A little bit baffled why T3 has reduced slightly when taking levo

elaine2447 profile image
15 Replies

Hi, about six weeks ago I was started on 25mcg of thyroxine. It was slightly earlier but I found i was not good with the mannitol in the Teva.

Anyway, yesterday did a 6 week follow up and this was the result

TSH 5.91 (21.3.22) 2.7 (29.6.22) (0.35 - 5.50 mU/L)

T3 5.2 (28.2.22) 4.6 (29.6.22) (3.5 - 6.5 pmol/L)

T4 13.9 (21.3.22) 16.0 (29.6.22) (10.5 - 21.0 pmol/L)

Is it usual for the T3 to reduce slightly when taking thyroxine. I haven't heard back from the GP, probably will be weeks before he gets around to it. I am taking it at night about 11.45 p.m. as it was too inconvenient with taking calcium supplements and fortified milk etc at breakfast time.

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elaine2447
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SlowDragon profile image
SlowDragonAdministrator

Standard starter dose of levothyroxine is 50mcg unless you are over 65 years old

Levothyroxine doesn’t top up failing thyroid, it replaces it….

Request next 25mcg dose increase in levothyroxine up to 50mcg and bloods retested again in another 6-8 weeks

ALWAYS Test thyroid levels early morning and last dose levothyroxine 24 hours before test

If you normally take levothyroxine at bedtime/in night ...adjust timings as follows prior to blood test

If testing Monday morning, delay Saturday evening dose levothyroxine until Sunday morning. Delay Sunday evening dose levothyroxine until after blood test on Monday morning. Take Monday evening dose levothyroxine as per normal

elaine2447 profile image
elaine2447 in reply to SlowDragon

Thanks. Well over 65 unfortunately. I can't request anything. This was taken up by locum. GP says won't make any difference to how I feel due to hashimotos. He'll probably ignore these results. It's only because I got them via my chart I saw them.

SlowDragon profile image
SlowDragonAdministrator in reply to elaine2447

So just because you start on 25mcg …you still have to increase the dose slowly upwards

Push for next dose increase

nice.org.uk/guidance/ng145/...

1.3.6 Consider starting levothyroxine at a dosage of 1.6 micrograms per kilogram of body weight per day (rounded to the nearest 25 micrograms) for adults under 65 with primary hypothyroidism and no history of cardiovascular disease.

1.3.7 Consider starting levothyroxine at a dosage of 25 to 50 micrograms per day with titration for adults aged 65 and over and adults with a history of cardiovascular disease.

So you will still need similar/same dose as some one under 65 …..but starting at lower dose and increasing dose upwards over several months

elaine2447 profile image
elaine2447 in reply to SlowDragon

Thank you

SlowDragon profile image
SlowDragonAdministrator

Teva brand upsets many people

Request GP add note to all future prescriptions “No Teva “

Have you had coeliac blood test done

elaine2447 profile image
elaine2447 in reply to SlowDragon

I'm on wockhardt and surgery does say that but Tesco pharmacy got it wrong twice.It's funny because one evening I had some gf sweet potato fries, mangetout and squash. I felt really ill into next day. When I checked all three high in natural mannitol.

SlowDragon profile image
SlowDragonAdministrator in reply to elaine2447

Wockhardt only make 25mcg tablets

Request double the number of 25mcg tablets as the increase in dose …..so that you can remain on same brand, at least initially

elaine2447 profile image
elaine2447 in reply to SlowDragon

This will make you laugh. Spoke to my GP today, he said 2.7 tsh is fine no need for doubling up the 25mcg!!!!! Men!!!!!!!

tattybogle profile image
tattybogle

It is not unusual to see fT3 level reduce when first starting levo .. (although it may increase again later as Levo dose is increased) It's to do with the TSH level ...

The thyroid normally makes a little bit of 'ready made' T3 in proportion to mostly T4 .... if the thyroid is failing and fT4 is lower than usual (so the TSH is high) ..... then the thyroid is clever .. in response to the high TSH , it increases the PROPORTION of T3 it makes ..bit like a safety net , to make sure there is enough readily available T3 to keep the important things going even if the fT4 level is a bit low .

once you take some levo and the TSH lowers, then this 'TSH boost for T3' stops happening ... so your often get people whose fT3 looked pretty good when diagnosed but then went lower again after levo was started.

in fact , the fT3 level they had at the time of diagnosis was probably a bit higher than what they usually had before their thyroid went wrong .. This is how thyroid levels usually change when they are failing:

~ fT4 may still look ok, but is a little bit lower than usual . so TSH goes up a bit ,

~ Then later as thyroid fails more ,fT4 falls lower and fT3 production goes higher to compensate , because TSH is now properly high too .

~ Then a while after that, when thyroid is totally knackered , and can't produce enough T4 or T3 enough no matter how high the TSH gets ,then the fT3 level falls too ..... most of us get diagnosed before this bit happens.

When you treat with levo , it lowers the TSH which unfortunately turns off the 'extra' T3 coming from the struggling thyroid , but there's no way round that .

As levo dose is increased and other things are optimised, then hopefully the conversion of T4 to T3 in the rest of the body increases fT3 levels again .. but once on levo we have basically lost that bit of T3 production that originally came direct from the thyroid .

elaine2447 profile image
elaine2447 in reply to tattybogle

Thanks so much for the explanation x

elaine2447 profile image
elaine2447 in reply to tattybogle

As you are so good at explaining I have a friend been on 75mcg for long time and said this"My Free T3 was in range after all these years. Perhaps you can ask her my predicament. WHy do I have normal TSH and top of the range T4. Do I need to reduce more? The answer isn't on the internet"

tattybogle profile image
tattybogle in reply to elaine2447

not sure i understand what her predicament is ?

people on levo with 'top of range' T4 can have in-range TSH .... and in-range fT3 .. nothing unusual about that mix of results

"do i need to reduce more ?" ... depends ....what is she trying to achieve ?

elaine2447 profile image
elaine2447 in reply to tattybogle

I think she worries a lot as we are both riddled with osteoporosis and she's been on thyroxine for such a long time wonders if it makes her bones worst having too much.

tattybogle profile image
tattybogle in reply to elaine2447

if her TSH is in range, and her fT3 is in range , and her fT4 is in range , and she has no symptoms of overmedication ... then there is absolutely no reason to believe that her dose is 'too much'

If it was too much T4 for her body's needs you would expect her TSH to fall below range , not stay comfortably in range.

Also ... all 'risks' in relation to thyroid hormone level are a question of balancing the risk of one thing, with the risk of another .....if we reduce thyroid hormone dose so much we don't feel well enough to be active / weight bearing etc .... then that is bad for bones too .

if she currently feels well on that dose, i wouldn't be too keen to mess with the dose just because of a high end fT4 ..... as long as it stayed in range, i'd leave well alone.

of course if she's very concerned about the high end fT4 level, she could always try a VERY slightly lower dose for a few months to see how it felt .. and if after a few months she still felt ok on a bit less ,then fine .

eg . She could try reducing her dose by 12.5mcg every day ( cut a 25mcg in half )

or even more subtle ....just reduce by 12.5mcg on 3 or 4 days a week and keep 75mcg for the others.

She would need to give it at least 6 weeks to settle , before testing and deciding how it felt, because the first few weeks often feel a bit rubbish /undermedicated when you reduce dose.

elaine2447 profile image
elaine2447 in reply to tattybogle

Many thanks, will pass it on x

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