Thyroid UK
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Blood test results and T3/T4 levels

I'm wondering if someone can help me with these results; i find it difficult to understand all the jargon.

i have been told that either my T3 or T4 is vastly out of range whereas the other is within range which apparently is unusual.Im sure someone here will understand what this means; Id really like to know..........I am on 50mcg of thyroxine at the moment and feeling a bit better on it i think; the tiredness seems to be abating anyway. But I had few other symptoms as far as I know; except. perhaps, a bit of brain fog

Results .

T4 8.4

T3 3.5 (I know this is low; does this indicate T3 replacement?

TSH 40.46 (which is better than it was)

Any comments very gratefully received.

7 Replies

Comment is difficult without knowing the ranges applying to each item. Please supply the ranges for these results, ranges are the figures in brackets after the results and those ranges are different for different labs then comment can be made. Would you mind also specifying exactly what the T3 and T4 are, though it is a pretty fair bet that they are FT4 and FT3, it is better to be accurate.

It is easy to see that the TSH is high, though. You need more treatment, that is obvious from the TSH alone. Other deductions can be made once the other ranges are known.

How long have you been having 50mcg thyroxine? When were you diagnosed and started on treatment?


OK thank you;


i have the range of T4which has recently apparently changed;These are the notes that went with it.; provisional range: 7.9 - 20.0 pmol/L

1st trimester low limit 6.7 pmol/L

2nd trimester low limit 5.8 pmol

3rd trimester low limit 6.1 pmol/l (I am 8.4pmol/L)

T3 range U 3.8 - 6.0 (I am 3.5 pmol/L)

TSH range u 0.34 - 5.6 (I am 40.4 mu/l)

Yes they are free T4 and T3

I was diagnosed just over 2 months ago, and began on 25mg; now have been on 50 mcg for just over a month. I have also been taking iron as my iron levels were very low indeed and its difficult to tell what has made the difference. My fear is that symtoms will start showing later on if I dont get my levels right now. Im due to be tested again in a couple of months time, over which time I will remain on 50mcg of levo.

Many thanks.


50mcg is a starting dose so it should be increased in about 4 to 6 weeks and be increased gradually so that clinical symptoms go and you feel much better. It is a gradual process and once you get to a dose which makes you feel well, it can stay that way unless you get other clinical symptoms. Most GP's keep you within a 'range' but he should be aiming for a TSH of 1 or less.

Get blood tests for Vit D, Vit B12, iron, ferritin and folate as many are deficient and should be towards the upper level.

You have to read and learn as much as possible about hypothyroidism so that you can assist in your recovery.

This is an excerpt - 0.05mg is 50mcg

Moreover, the dose he prescribed, 0.05 mg, is extremely small. It’s so extremely small that it's highly unlikely you'll benefit from it in any way no matter how long you take it. On the other hand, that small a dose may actually slow your metabolism more and worsen your symptoms


Thank you. That doesnt sound too good. Im not having another blood test for a couple of months; is this bad management? What is a 'decent' dose? Its disturbing to me that you say the levo will slow my metabolism; i think its slow enough already!

Im not actually aware of any symptoms apart from tiredness; and more laterly suffering greatly from the cold, but i have been an insomniac for the last 18 years and so grew used to it. Either the iron or the levo I am taking have helped a little with my energy levels, and i feel brighter. Symptoms may of course have been accepted by me and go unnoticed.


Hi the levo at that small dose will slow the metabolism but when you reach an optimal amount your metabolism should correct itself. Please leave at least 4 hours between taking your levo and the iron as it will interfere with the absorption of the levo. If ypu have been on 50mcg for 4 weeks now I would think about going back to the doctor and getting another blood test and hopefully more levo. Take care.

Jo xx


Thank you .... they were not going to test again till may: Im not feeling ill, will there be bad consequences if I'm not tested till then? Thanks for the iron tip.


You might be alright. Everybody is different. If you do feel yourself going back again to feeling tired and brain fog getting worse I would go back to the doctor and tell him. Why are they leaving you 3 months at 50mcg if after 4 weeks they raised you from 25mcg. If you are feeling alright I wouldn't worry. Its all about you feel 'cause we are all different. Take care.

Jo xx


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