T4 unchanging on Levothyroxine - is this normal?

[Bluedog123]

Hi everyone,

So in November 2018 I was diagnosed with subclinical hypothyroidism, with levels of:

Serum TSH: 5.1mu/L

Serum free T4: 13.7 pmol/L

However, I was experiencing a lot of symptoms so the GP agreed to a trial dose of Levothyroxine starting at 50micrograms daily.

I've recently gone back for blood tests and the results are as follows:

Serum TSH: 4.32 mu/L

Serum Free T4: 13.8 pmol/L

The GP has said he would like to see more of a result so has upped my dose of Levothyroxine to 100micrograms daily.

However, I am a little confused and very anxious about the result.

Shouldn't my T4 have been raised by more than 0.1 in 2months on treatment?

And how has my TSH come down but my T4 not gone up?

Could someone please explain and help put my mind at rest? As anxiety running very high that something more serious is wrong

Thanks in advance.

[Serenapuff]

Hi Bluedog, I am curious what others will say as I am in a similar situation. After previous dose increase, my TSH lowered a bit but my free T4 stayed where it was. This last dose increase both my TSH and free T4 level went in the wrong direction which didn’t seem to bother my endo as both were in normal range but not the optimal end of normal. I don’t get it. Sorry I can’t be helpful but hoping someone will have some ideas.

[Bluedog123 in reply to Serenapuff]

Hi Serenapuff!

Thanks for responding, it's calming to know that I'm not alone at least!

Here's hoping someone can respond and let us know what's going on haha

[diogenes Remembering]

Its probable that your dose of T4 has led to an increase in T4-T3 conversion which has cancelled out the T4 added but raised FT3. You may need quite a bit more to overcome this tendency but this might further raise your FT3. However, it's the FT3 that should be measured because FT4 is only an indirect marker of function. Your TSH will be slow to respond to treatment as it is only 2-3 months since beginning treatment. TSH has a delayed response to alterations in thyroid hormone levels.

[Bluedog123 in reply to diogenes]

Hi Diogenes,

That actually makes a lot of sense. Thank you for your answer, definitely helped to calm me down. It's just difficult when you first get a diagnosis there doesn't seem to be a lot of info out there and it can be really scary, especially with results like this.

Thanks again

[SlowDragon Administrator]

It's standard practice to start on 50mcg Levothyroxine, retest bloods 6-8 weeks later

Then dose is normally increased in 25mcg steps until TSH is under 2, FT4 in top third of range and symptoms improving

It's good your GP recognises you need dose increase

You may find jump up to 100mcg in one go is a bit much, or it may be fine

Bloods should be retested 6-8 weeks later

NICE guidelines on How to introduce and increase dose

cks.nice.org.uk/hypothyroid...

Recommended on here that all thyroid blood tests should ideally be done as early as possible in morning and fasting. Do not take Levothyroxine dose in the 24 hours prior to test, delay and take immediately after blood draw. This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip, best not mentioned to GP or phlebotomist)

Has GP tested TPO and TG Thyroid antibodies, vitamin D, folate, ferritin and B12. If not ask they are tested at next blood test

Anxiety is common hypothyroid symptom, it should Improve as higher dose slowly kicks in

thyroiduk.org.uk/tuk/about_...

[Bluedog123]

Hi SlowDragon,

Many thanks for your in-depth reply, this is really helpful for a Thyroid newbie like myself I'm unsure if those other tests have been run, as cannot see them here, so will check with the GP and ask for them to be added to next blood test if not.

Good to know the info about Anxiety as well. Feeling a lot calmer after having people explain this to me, having a forum is really helpful for this kind of this, as it's good to get the experience of people who have been on this journey longer than me!

Thanks again!

[greygoose]

Did your doctor tell you how to take your levo? On an empty stomach, leaving at least one hour before eating or drinking anything other than water, and at least two hours before taking other medication or supplements - for some of them, you need to leave four hours.

[Bluedog123 in reply to greygoose]

Hi Greygoose,

Yes thank you, the GP was pretty good at explaining and the pharmacist was also kind enough to go through the leaflet with me and explain the best time to take it and how long to leave before food / other meds

[greygoose in reply to Bluedog123]

Good. They often don't.

[Wetsuiter in reply to Bluedog123]

we all like your Dr already

[Tristy]

My T4 (and T3) stayed low however much the Levothyroxine was increased. I got to 175mcg daily and it was still the same low level. I decided to add a tiny amount of t3 and I couldn’t believe the results. Both T4 and t3 shot up. I’m now fine. Not to say it will be the same for you but wanted to share my experience.