T4 result help please

[Zmalp]

Hi, just asking for a spot of advice on interpreting this:

Husband’s TSH has dropped from 6.67 to 4.32 after 7 weeks on 50mcg Levothyroxine (up from 25mcg. This is great because he’s felt significantly better. His dose will go up now as the target is just under 1.

But his T4 has dropped from 12 to 10.5 and the target is top of range so around 14. Does this drop mean anything significant or is it a usual thing at first?

No T3 or vit results this time as an NHS test.

I know this is a really early stage but he has been so very ill with this undiagnosed for so long that I’m trying to understand as much as possible to track symptom severity against his bloods as a pattern to talk to the private endo at our February appointment so thanks in advance for any help

[tattybogle]

hi , it's not unusual for the fT4 to drop a bit while doses are being adjusted . It will improve again as his dose is increased to closer the full expected dose .

What happens is when some T4 is added, the TSH falls, but then the 'lower' TSH is not asking his own thyroid to try so hard to make T4 anymore so his own T4 production goes down .

Simplified example:

say you need '100' but your own thyroid is only able to make 75

So the GP adds 25 ... so for a few weeks you have 100.

But then the pituitary 'notices' it went up rapidly to 100 and thinks "oh good ,the thyroid has started working, i can stop shouting at it to make more T4 " .. so the pituitary lowers the TSH signal ( the pituitary is a bit thick , and it doesn't realise that the extra actually came from a tablet)

then due to the lower TSH the thyroid stops making 75 and only makes 25 ..

So now you only have 50 .

Then the GP puts the dose up again .

and this balancing act continues until you get what you need , and the TSH is low enough that the sum stays balanced.

Simples

[Zmalp in reply to tattybogle]

Great, thank you 😊 I really appreciate the explanation - he’ll understand that (which is massive progress in itself as 2 months ago he wouldn’t have been able to follow any of it 🥳)

[SlowDragon Administrator]

So he’s ready for m next dose increase in levothyroxine up to 75mcg

Which brand of levothyroxine is 50mcg tablets

Ideally don’t change brand…….only change one thing at a time

Stay on same brand as 50mcg and increase to 75mcg

Retest again in another 6-8 weeks

Likely to need further increase in levothyroxine after next test

Has he had vitamin D, folate, ferritin and B12 levels tested

Is he currently taking any vitamin supplements

[Zmalp in reply to SlowDragon]

Thanks, I’m going to ask for the same brand again and if they will give a 25 and 50 pack in case he needs to take an evening and morning dose when it increases. He had some ‘hyper’ symptoms last time the dose went up for a week but it settled.

He had the full thyroid panel with vit D etc in October and I’ll get another soon to check his vit and mineral levels, especially folate and vit D which he’s had issues with in the past.

He’s on a thorough range of supplements (followed what you advise generally and adjust to his blood results). He stopped biotin a week before the tests.

You have been a great help understanding the importance of optimising vitamins and minerals because the doctors rarely cover it 😊

[SlowDragon Administrator in reply to Zmalp]

which brand is he taking

Accord don’t make 25mcg tablets

[Zmalp]

Accord but he had 25mg Wockhardt before that and doubled up when he first increased and didn’t show any reaction on that change

Edited as: better to get just 50 mcg and split?

[Cornwaller]

Pleased to hear your husband is beginning to get better. You mentioned monitoring symptoms against bloods. I think symptom monitoring is undervalued, especially by GPS, as it a measure of hypothyroidism itself. A couple of measures which are numbers and interesting to trend are temperature and heart rate. Obviously these need to be taken at similar times and under similar conditions.

Best wishes.

[Zmalp in reply to Cornwaller]

Thank you, and a really good point. I’ve been tracking his temperature for a while but hadn’t thought of heart rate.

Interestingly, one of his symptoms is mental confusion. When I started tracking his temperature, I realised it’s at its worst when his body temperature drops below 36 degrees C. This is often early evening when he was getting very tired and aches and tinnitus got worse.

Since he’s been on 50mcg Levo, it’s never dropped that low and the confusion is much improved. So is evening energy.

I think he has a heart rate monitor on his watch so will take a look 👍