T4 conversion to t3 question

[Ralph1985]

Hopefully some one can share some information on this subject. Alright, so lets say I took t4 only medication 2 hours before blood test, I know the tsh won’t change much if it even does but how about our free t3 will it be higher at the blood test than let’s say if I had taken the medication 24 hours prior to the blood test? Or is it like the tsh..

[Lalatoot]

I am not science minded but I don't think T3 would be affected as T4 is a storage hormone. What we take today is stored and then converted as the cells require it. Helvella is the one to answer this!

[Hay2016 in reply to Lalatoot]

That’s my gut feeling too. 😀

[Ralph1985 in reply to Lalatoot]

Alright, but it’s been show that if you take t4 medicine before a blood test your total t4 will be higher at that blood test so would this cause more conversion to t3?

[Lalatoot in reply to Ralph1985]

But t4 is a storage hormone. It converts when the cells require it. Need a science person on this.

[Ralph1985 in reply to Lalatoot]

Alright, thanks for replying I stick to our theory untill a scientist shows up. 😆

[helvella Administrator in reply to Lalatoot]

Not a scientist here!

The peak T3 effect of a dose of T4 usually occurs around 48 hours after ingestion. (Which doesn't mean it will just sit there with no impact whatsoever for 48 hours.)

Levothyroxine (T4) tablets are allowed to contain up to 1% T3 - as an impurity. (Apparently, liquid levothyroxine products conatin less T3 for some reason.)

Although many regard T4 as a storage hormone, the body converts it not just in cells but also to maintain a certain level in the blood. That is, whenever the level in the bloodstream drops, conversion should be triggered to maintain the level. This will be ahead of the time at which the individual cells need it.

Also, remember that while we tend to talk about T3 as being available because the cells need it, the classic theories of hormones talk about hormones sending a signal to the cells.

[greygoose]

Pretty certain that taking your levo before the blood draw would not affect either the TSH or the FT3. Just the FT4. Things don't work that fast with hormones.

[Ralph1985 in reply to greygoose]

Oh alright I was just curious. Usually I take my t4 med 24 hour before blood test. But last test I took 3 hours before bloodwork and my tsh came back at midrange and my ft3 a little bit over range

[greygoose in reply to Ralph1985]

That's strange, to have a high TSH and over-range FT3. Do you you have Hashi's?

TSH level changes with the time of day. It's highest early in the morning, and drops throughout the day. But, if TSH were affected by taking your levo before the blood draw, it would be lower, not higher.

[Ralph1985 in reply to greygoose]

I do have hashis but I don’t think it was a hashis attack I didn’t feel over anxious or anything... I have gotten hashis attack before and usually when they happen I feel great because of the ft3 boost... my numbers were the following...Tsh 2.85 0.35 - 4.94

T3 free 4.54 2.5 - 4.50

[greygoose in reply to Ralph1985]

You don't have to have a full on Hashi's 'hyper' swing for your numbers to jump around. They can do it all the time with Hashi's. And, when the Frees rise, the TSH is very slow to follow.

Funny, most people feel awful when having a 'hyper' swing. But, I used to feel great, too! Loads of energy, sudden weight loss, hair began to grow… I had my last one when I was 50. It's been all down-hill since then.

[SPD1 in reply to greygoose]

Hi Greygoose,

could i just ask when you experienced a hashi swing to Hyper did you ever experience arm or leg tremors, leg weakness, breathlessness, palpitations at all?

How often did the swings occur and how long did they used to last?

Thanks very much.

[greygoose in reply to SPD1]

No, didn't experience any of those. But, we're all different, and other people might. As far as I know, and it's rather difficult to know because I probably developed Hashi's at around 8 years old, and wasn't diagnosed - or even tested for thyroid - until I was 55, but going by symptoms, I only had about four or five in my whole life. And, they tended to last quite a while, followed by a long period of euthyroidism. But, as I say, my thyroid was never tested, so it's all guess work, going on symptoms only - or lack of symptoms. I really can't give you any precise detail, I'm afraid. And, as I said, we're all different.

But, I would say that your list of symptoms sound more like hypo than hyper.

[SPD1 in reply to greygoose]

Hi, thanks for that.

Hypo symptoms? i thought tremors, palpitations etc were associated with Over medicated rather than under medicated ? I'm really confused now.

[greygoose in reply to SPD1]

There isn't a rigid dividing line between hypo and hyper symptoms. This is a mistake so many people make. So many symptoms can be both hypo and hyper. Come to that, the majority of hypo/hyper symptoms can be due to a lot of other things, too. Tremors can be caused by a lot of things. But palpitations can be both hypo and hyper - they are definitely not just a hyper symptom. And, I would say that leg weakness - muscle weakness in general - is more likely to be hypo than hyper. It dangerous to go by symptoms alone unless you know your body very, very well.

[SPD1 in reply to greygoose]

Thank you greygoose,

i hear what you say, its all very confusing as to what is going on after being so well for 15 years on Actavis, then starting with the aforementioned symptoms, swopping to Mercury Pharma and things settling down for 3 months and now all of a sudden back to symptoms again after what appears to have been a trigger and reacting to the constituents in Lemsip all in one.

I am not sure whether to go to doctors or leave for a few more days, its been a week now since symptoms restarted, the dilemma i have is i know my GP will immediately suggest a reduction again and obviously that might not be what is required and i will then have no chance to ever get it increased again on the NHS. i feel so isolated and worried with this, don't know what to do for the best. Its my heart more than the tremors thats concerning me, raised heart rate continuously, my resting heart beat is normally 60 but has been fluctuating between 65-75, doesnt sound a great deal but i can definitely feel the difference, particularly when i am absolutely still

[greygoose in reply to SPD1]

You could try reducing your dose on your own, see if it helps. But, don't tell your doctor. Then, if it doesn't help, you can just put it back up again. That way you will know if your really need a reduction, of if you really don't!

I only once ever tried a Lemsip, about 50 years ago. It made me so ill, I've never had one since!

[SPD1 in reply to greygoose]

Good call, i was actually thinking about trying reducing myself. the pill cutter i have is absolutely useless though, dont get even split and also loads of powder crumbs so impossible to get even amounts, is there a particular cutter on the market you know about which is supposed to be better than the rubbish ones from the chemists??

I wont be going near Lemsip again now!

many thanks.

[greygoose in reply to SPD1]

I bought mine in Sainsbury's over ten years ago, and it's still going strong. I have no idea what's on the market today, I'm afraid. But, it doesn't matter that much if there are crumbs or the dose isn't that equal. T4 is basically a storage hormone, so it's ok if you have a little more one day, and a little less the next. And, the crumbs can just be swept up and popped in your mouth. I have to split one of my T3 tablets, and that's what I do.

[SPD1 in reply to greygoose]

Ok, i shall try that

Thanks very much for your suggestions and assistance.

Have an enjoyable weekend

[greygoose in reply to SPD1]

You're welcome. Hope your weekend is good, too.

[SPD1 in reply to greygoose]

Thanks

[Lora7again in reply to greygoose]

I felt great at first but then I became too hyper and felt dreadful. I think I may be slightly hyper now but the NHS says the TSH of 0.70 is perfect so N/A was put on my blood results. I will be doing my own blood test next week so I will be interested to see what my T4 and T3 says.

[greygoose in reply to Lora7again]

Well, I have Hashi's, not Grave's. So, not at all the same thing.

[Lora7again in reply to greygoose]

No, but some of the symptoms are similar like hair loss etc.

[greygoose in reply to Lora7again]

Well, yes, but I meant hormone levels.

[Lora7again in reply to greygoose]

Ok I get what you mean... what I don't understand is why I am sometimes underactive if I have Graves' ... that is a mystery to me but Dr Skinner did say he had come across some people like me and he was an expert imho.

[greygoose in reply to Lora7again]

Were your Grave's antibodies positive: TRAB or TSI?

[Lora7again in reply to greygoose]

I am not sure I will have to fish out results from over 10 years ago. The Consultant who scanned my multinodular goitre last year told me that I definitely did not have Hashimoto's because mine looked nothing like someone who was suffering from it. She said that she had scanned hundreds and knew exactly what they looked like and mine looked like Graves' Disease to her.

[greygoose in reply to Lora7again]

OK, but I'm not a very trusting soul. I don't think I would just have taken her word for it. lol

[Lora7again in reply to greygoose]

Well she is a well respected Consultant who is in her 60s so I did trust her more than others I have seen. The nurse who was there told me she was very good and would know straight away if it was cancer. She did take a long time examining my neck and scanning it and even scanned the top of my chest because I told her I had a fat pad there.

[Hidden in reply to Ralph1985]

When I was on levo only, I was once tested about four hours after ingesting it. My levels - TSH, FT4, and FT3 - remained the same as when I had not taken levo for 24 h prior to having labs done. My TSH was suppressed at the time (0.05) because my doctor wanted a TSH between 0-0.05 in patients with Hashimoto's. I required 200 mcg of levo daily to achieve that and I felt much better than on lower doses that kept my TSH in range (where most doctors are happy to see it). I imagine an in-range TSH is the only thing than can vary noticeably in a 24 h period (although mine was already suppressed so no change there), that FT4 levels will remain stable for at least a week after ingestion given it's relatively long half-life, and the same goes for FT3 levels...in my own experience, FT3 levels will only change noticeably during during the day if on NDT or T3, hence the advice to leave 8-12 hours before having labs if on drugs containing T3.