Thyroid UK
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Can anyone help with my thyroid results please?


I have just had my blood results back. I used to take 150mg and was reduced to 100mg, big jump !!

I have all the classic symptoms of my thyroid being underactive but wondered if someone could interoperate my results.

They are

Free Thyroxine 17

Free Tri-iodothyronine 2.9

TSH 0.1

I do not understand what the three results mean.

Many thank to anyone who can help.



7 Replies

Glennie, we need to see the lab ref ranges (the figures in brackets after results) to interpret. Were you taking 100mcg or 150mcg when the bloods were tested?


Ok I only got the results over the telephone. I was taking 100mcg when I had the test. How do I get the lab ref ranges?


From your surgery - ask for a copy of your latest results with ranges. It is your entitlement....

Without the ranges - it looks to me as if your FT3 is low.... so you could be experiencing a conversion problem.

How are your levels of Ferritin - Folate - B12 - Iron - VitD ? if low in range they could be affecting the conversion of your Levo dose into the Active T3....



I have just found some ranges from 2013

Serum TSH level (.27-4.2)

Serum level free T4 (12.0-22.0)

Serum free T3 level (3.9-6.8)

Does this help



TSH 0.1 (0.27-4.2) is below range. Which should mean FT4 and FT3 levels are adequate but yours are low/deficient.

Free Thyroxine 17 (12-22) is halfway through range. It needs to be in the upper quadrant of range >17-22, perhaps even slightly over for you to convert sufficient T3 if you are on Levothyroxine.

Free Tri-iodothyronine 2.9 (3.9-6.8) is below range. Low T3 causes hypothyroid symptoms. It needs to be halfway to 2/3 through range >5.35.

A Levothyroxine dose increase will raise FT4 but I don't think it will do much for FT3. Ideally, 10-20mcg T3 will be added to your existing Levothyroxine dose to improve your FT3. Some GPs are able to prescribe T3 but some are instructed not to do so without the recommendation of an NHS endo. Another option is to buy on the internet and self medicate.


Thank you for your reply.

So I don't need to increase my levothyroxine which is what I thought but take another tablet T3 to improve my hypothyroid symptoms.

Do you know were this can be bought on the internet ?


It is possible that the pathology lab that carried out your tests publishes their reference ranges on the web. There are no guarantees... My local path lab doesn't publish but I have seen them on the web from other NHS labs. If you find something that fits the bill make sure it is valid and current. Ranges change quite often.

Oh, and another thing... You must only use the reference ranges for the lab that did your tests. You can't just pick any lab and use theirs.


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