Thyroid UK
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Advice on TSH Free Thyroxine and Free T3 results please


I have just received my results back from Blue Horizon

Tested 5/6/2013 Active B12 level 125 (Range 25.1 - 165.0)

Free T 3 level 4.1 (Range 3.1 - 6.8)

They could not test TSH or Free Thyroxine as not enough blood so sent me another kit to take blood again

On 15/06/2013 TSH level 0.49 (Range 0.27 - 4.2)

Free Thyroxine 20.1 (Range 12.0 - 22.0)

Free T3 level 3.7 (Range 3.1 - 6.8)

Can someone please comment on the results, I think the TSH and Free Thyroxine look quite good but I do not know about the Free T 3 and is it good or bad the level has altered in 10 days, also is the Active B12 good, I have been using Vit B12 Spray for 4 weeks 2400 ug daily so should I carry on using it. Original Test at G.P. for B12 was 377

Many thanks and Kind Regards browny

6 Replies

Hi browny,

How are you feeling and are you on any medication?

the fT3 level looks low to me. Just wondering, did you have the blood taken at different times of the day each time, or the same? Personally I would need my fT3 to be higher - I have the same range in our lab and need mine to be about 5.8 to feel well, but we are all different.

I suspect, if you are on thyroxine, that these results might indicate a conversion problem - fT4 quite high in range and fT3 quite low in range. If this is the case, then it would indicate that you might benefit from the addition of some T3.

Sorry can't comment on the active B12 test... xxx



Thanks for your reply, sorry I should have said I am on 100mcg Levothyroxine which was increased from 75mcg five weeks ago. I did both tests about the same time, around mid morning. I did start to feel better around the time of the first test but I feel I have gone back wards this week

Regards browny



Just thinking about it I think I took my blood for the first test mid morning and

nearer lunch time for the second test, so could this have made a difference to result of FT3


That could have made a difference to your fT3. Rod posted something a while ago showing that whilst TSH levels are lowest early in the morning and highest later in the day, the opposite appears to be true for fT3 and fT4. So your fT3 might be a bit lower because it is later in the day. However, both results look too low to me. I still think this could indicate a conversion problem, and that you might benefit from some T3. xx


Thanks, I will see how I go and talk to my G.P. re the T3 and ask for a referal to an endo

as from reading on here I know that G.P's won't prescribe it. Do you know if the TSH and FT4 are O.K. to be at their present level with the T3 in the low range

Thankyou browny


The doctors will probably think they are fine as everything is in range, but I suspect your ft3 is too low and that you have a conversion problem. Xx


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