Thyroid UK
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High T4

Having upped my Thyroxine my blood tests came back with a T4 of 29 (Range 12.5-20.5). As I have mentioned previously my endo wants to now reduce my Thyroxine again due to the "dangerous" level. I feel much much better. What I want to know is how "dangerous" is a T4 level of 29? I have NO symptoms whatsoever of being hyper. (How can I be I am a HYPOthroid patient.) Endp speaks of bone problems and stroke but my pulse rate is 75-80. Blood pressure is fine.

8 Replies

Did you take your thyroxine just before the blood test. This could show skewd results. Getting T3 tested is always an issue with the NHS but perhaps you have a conversion problem. On the other hand if you are feeling okay something is working. I am sorry but I don't know how dangerous a T4 level of 29 is, but I am sure someone will be along to give you some help on this.


I have never seen any proof that having a high Free T4 or undetectable TSH is dangerous, unfortunately doctors say this but where is the evidence?

I feel well when my TSH is usually undetectable and my Free T4 around 23.9 (range 9 to 19) and ofcourse if this was my GP looking at my levels then she would insist that I take a reduction in thyroid meds. The fact that I have convinced my Endo (out of my area) that I can barely function if I do lower my dose, then my GP listens to my Endo.

I cannot see the point in a doctor being happy with a blood test result number (which is hardly going to be reliable) if the patient feels dreadful, are doctors wanting us to be well ? or are they more concerned with lab results?

I think there is more chance of there being a link between hypothyroidism and hear attacks when people are un-diagnosed or under medicated!

You can have a spike in your result if you have taken your thyroid medication just before the blood test. If you take yours in the morning, then I would have my bloods done as early as possible (hospitals open at 8am) and then take your thyroid meds.

How do you feel?


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Thanks. I have started taking my meds at night as there is a better absorption factor if I do this. This may of course mean I have managed to up my T4 level. I am prepared to reduce my meds very slightly but will be keeping an eye on how I feel as last time I did this everything got much worse including my fibromyalgia. I can understand her concern if I had a thumping racing heart and the shakes or couldn't sleep etc etc but none of this is the case. I just function much better with a high t4. I don't think that I am so far out of range that I am in a danger zone but my endo seems to think so.


If I were you and felt as good as you obviously do, there would be no reduction in meds. The doctor can't make you and Its supposed to be team work.

Jo xx


Searching for info (in Australia), found these posts. Good to know other people share the same problem. Saw endo - T4 was a bit high in test (although did take meds beforehand) and TSH very low (which it always is regardless of T4 result) - but feeling much better than I have in a very long time (also due to dietary changes eliminating goitrogenic foods). Endo is happy with my 'whole picture' but GP is not. You are lucky that your GP will listen to your endo - mine won't and always insists I reduce my thyroxine - which always results in my becoming hypo - so stopped doing that a long time ago. She was extremely rude in joint appointment with endo, insisting I take vitamin D and have bone density scan - even snapped at the endo who was trying to tell her all is ok and that results are very individual. Time for a new GP I think.


my doc keeps going on about this.

It's actually boring me because I don't know where this normal level came from......... what is normal? who is normal? Why do you care so much about me being above normal but don't do anything when my T3 is below normal eh? I feel for you QueenBee. I've had this argument with my Dr.

There is a RISK but then everything has a risk. Just as taking not enough for you to feel well is a risk. They need to bin the blood test and treat on symptoms like they used to. Everything has a risk. I functioned so much better, head felt clearer, skin became soft, my constipation went, i slept so well. Then they panicked and told me to drop my dose again.

Has your T3 gone up since taking more T4? I found mine does. And then when they reduce it the T3 goes down again surprise surprise. They don't even give me long enough to stabilise on a higher dose- i reckon you need at least 6-8 weeks to see changes. Yes somethings feel better over night but the body has to adjust.

They just panic. I get calls from the surgery when my T4 is like 1 over normal; yet when I'm obviously hypo they leave it for a year before telling me.... *rolls eyes*

Even if you take your meds and night, don't take it the night before a test too. Hope something sorts out for you xx


I have the same problem. I know I feel better when T4 is above the range and TSH is completely suppressed, but endo will not allow my TSH to be suppressed.

The research that they have pounced on which shows a link between low TSH and osteoporosis was a retrospective study done in Dundee (sorry I did have a copy of it but not to hand, will have a look for it). But I think it is flawed in that they didn't have data for levels of T4 so it wasn't taken into consideration.

My gp says it's only really in the past 5 or 6 years that they have been saying this, ie since this research was published, and another endo told me just 7 years ago that low TSH wasn't a problem - he said it is only a problem where you've previously had hyperthyroidism. My interpretation of this is: it's not a problem having no TSH, the problem is too much T4/T3. But if you have no HYPER symptoms, having a T4 just high enough to relieve HYPO symptoms then you are not hyperthyroid, therefore there's no risk!


Hi,,, I've recently re read my Dr toft book , which specifically says that most people feel well with a tsh very low in range plus ft4 high in range or even just above as long as ft3 is normal,, maybe someone can provide a link on here,, also that range you quote only goes to 20,, which seems little low to me, do you know what your tsh is? I recently paid out and had mine done via blue horizon , i now have good complete idea of things, money well spent !


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