Are ft4 levels important?

[Kandahar]

Think my headline says it all. If ft3 Reading is good, do we need high amounts of ft4 if we can’t convert

It?

[greygoose]

Well, no, it doesn't say it all. It depends on what you're taking, and you didn't say that. And, it depends on the person. Some people need quite a high level of FT4, even if they're taking T4+T3. Other people are happiest with zero T4 - like me.

If you're taking T3 only - like me - your FT4 is going to be zero, and for some people that's fine.

If you're taking T4+T3, your FT4 will be low - lower for some than for others - and that's ok for some people, but others need it higher.

There is no one-size-fits-all with thyroid hormone therapy - something doctors have yet to discover - you have to experiment for find what's best for you. And, it's mainly about how you feel, rather than blood test results. They're just a vague guide, rather than a rigid rule. So, there is no absolute anser to that question, no matter how much you say.

[NWA6]

Hey Kandahar 😊 I need both to be High in range in order to feel optimal. It seems unusual doesn’t it? If T4 is inactive then why do we need an optimal level when taken T3 and T3 being optimal? 🤷‍♀️ I don’t know. Could be that we don’t know all there is to know about T4. In fact I have had a very high t4 result with a low T3 and felt hyper, go figure 😉

So overall, the answer for me is YES FT4 levels matter. HTH 😊

[Hidden in reply to NWA6]

I'm the same! I have felt worse lately and got my most recent lab results today: FT4 levels at bottom of range so I am going to add some T4 to a slightly decreased dose of NDT. My FT4 levels came back at 0.7 (ref 0.7-1.5) and I need them around 1.1-1.2 to feel optimal - along with FT3 levels in the upper third of range. It can take some tweaking to achieve, and I realise I will need to combine NDT and T4 rather than take NDT alone, but to answer your question: yes, to some of us, FT4 levels do matter.

[blondpalomino]

Hi Kandahar,

Personally I can't take too much T4 as it causes me palpitations and high blood pressure.I am on 20mcg T3 and 75mcg T4, and that is all the T4 I can tolerate.