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Blood test - fT3 fT4 and TSH

Blood test - fT3 fT4 and TSH

I was interested to my ft3 and ft4, because i am always tired and gained weight.so i did a blood test.

And this are my results :

fT4: 12.8 pmol/l. Reference : 10-28.0 pmol/l

fT3 : 4.3 pmol/l. Reference : 3.0 -9.5 pmol/l

TSH: 2.096 mU/l Reference : 0.1 - 4.0 mU/l

I would be happy to receive some interpretations of these values form experienced users.

I am thinking to take an appointment by a doctor. But i am not sure, if it is really necessary...

Thanks niclas.

Ps: i have Not been on Medicaton yet. And i have Not visited any doctors yet, regarding this.

18 Replies

niclassutter Can you please edit your post and put the reference ranges in (click the down arrow, choose edit, make changes, click the green button 'Edit response'). As ranges vary from lab to lab it's not possible to comment accurately without them.

Did you also have antibodies tested?

Are you looking for a diagnosis or are you already diagnosed hypothyroid and on Levo?



Welcome to our forum.

If you supply the test ranges (numbers in brackets) and advise whether you are medicating thyroid hormone replacement (or not), members will comment.


A TSH of over 2 is above average (most people fall within the range 0.5 to 1.5) but nowhere near high enough to be diagnosed hypothyroid. Most doctors go by the TSH, some will take into account low (below range) FT4 and most ignore the FT3 (if they even test it). You won't get a diagnosis until your TSH is over range, and some doctors in the UK make you wait until your TSH is over 10.

Having said that, your FT4 and FT3 are near the bottom of the ranges. So what do you do? You could either look for another cause of your tiredness (eg low iron) or you could get your own NDT (eg Armour, erfa, thiroyd, nature throid, thyroid-s.....) and try treating yourself. You would need to read up on hypo and hyper symptoms and listen to your body so that you know whether it is working for you or not.

Best of luck


Thank you fo your reply !

I think i will try to Supplement Arsen and Jod for 1 month,, maybe that increases my own t3 and t4 production.

Otherwise i would treat myself.

What happens if i take a 25mcg t3 pill, how.much does it.increase my ft3 Level?

Is there any calculating method ?


25mcg of T3 is quite a heafty dose. I would start with 5mcg for a couple of weeks, then move to 10 if you feel you need it. 10 mcg of T3 is approximately equal to 50 mcg of T4. Your freeT3 should be as high as possible within the range. Good luck.

1 like

Ok fine, i will make another blood test after medication.

What would be the earliest timeframe to do a retest ? 2 weeks ?

If my ft3 increases , my STH should get low right ?



25mcg T3 is equivalent to 75mcg Levothyroxine, possibly a little too much to start on. You could take 12.5mcg and retest in 6-8 weeks. TSH reduces as FT3 rises.


I'm currently in battle with my doc to get a hypo diagnosis and to be honest it's proving to be quite difficult - I think I've now got her to refer me to an endo! I've looked into self medicating but am reluctant to do it just yet. Blood results have shown I'm low in B12, folate & vit D so want to get them all in order before I start to self medicate.

What's Arsen & Jod please?


Arsen and Iodine are necessary for our body to convert t4 to t3

As much as i know.

But if you have already low t4 levels then these two substances won't really help.


Ah I see.

It's my T4 that's low(ish) & TSH is mid range - yet I still feel rubbish.


Sorry .... Iodine is necessary to build t4. So it can help !!

Arsene is important to convert t4 to t3.


Maybe I should try iodine & see what happens.

I'll have a look into it - thanks for the info.


The general rule of thumb for ranges are

FT4 55-60% of the range. So should be around 20

FT3 75-80% of the range should be about 9

And a TSH 1 or below all things being normal they should rise equally

Hope that helps,

1 like

thanks, my values are definitely low.


Both your FT3 and FT4 are quite low. The one that makes you feel well (FT3) is only 20% up into its range. You need FT3 to be 50%-100% up in its range.

This shows you why TSH is usually irrelevant! And why reference ranges, like most lab reference ranges, are too broad. Probably 90% of doctors who looked at this, would tell you that you are "normal" and perhaps try to put you on an anti-depressant.

If I were you, I would fix all the nutritionals you'll find commented on all over this board. Then if that does not improve things, go on T4 until you can get your FT4 at least 50% up into its range. If that does not fix your FT3, then you will have to add in T3, or go on NDT. Whatever you do, don't let this go on a long time, because low T3 can lead your adrenals to try to compensate, and they will eventually go into fatigue.


BTW, an appointment with a doctor isn't absolutely necessary, and can actually lead you astray if it is an ignorant doctor. There are people on this board who treat themselves. You can get T3 and T4 off various websites, if it turns out that is what you need.

Forgot to mention that you should try to find out if your low thyroid is due to Hashimoto's. You need to have the TPO and TG antibody tests. If you have anti-thyroid antibodies, it is a huge plus to your health if you find out what is causing them.


Hi thank you very much for your advise !!

I dont think , that its Hashimoto's. Because those antibodies are low.

Now i have attached my lab results, with all of these values


Your test is terrific, you could only check your iron, b12, cortisol levels, everything is ok with your thyroid. Eat more veggies and less fat foods. Fatty foods could make you weak and also gain weight.


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