Thyroid UK
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T3 Results


Since 1994 after a partial thyroidectomy for Graves Disease I have been on 200mcg Levo. Over the last 2/3 years my GPs have asked me to reduce my dose as they told me I have been overmedicated. I am now taking 100mcg. I recently had a Blue Horizon test which included T3 which to my knowledge has not been tested before.

Here are my results:

TSH 0.039 ( reference range 0.270 - 4.2)

Free T4 26.98 ( 12-22)

Free T3 3.8 ( 3.1-6.8)

My TSH and Free T4 have risen since my last test ( though my dose of Levo was the same) but I do not understand the significance of the T3 result.

Can you help?

3 Replies

Was there an approx 24hours between your last dose and the blood test?


Yes, I take my Levo in the evening so having missed my normal dose it was at least 36 hours.



Then I've no idea why your FT4 is so high then unless you have difficulty converting it as your FT3 is lowish. This is what I've copied from the link below:

If the Free T3 level is significantly lower than the Free T4 level, it is next to useless to treat with Synthroid/ Levoxyl/Levothroid (T4) only replacements. If the patient could not muster sufficient T3 from their gland (which produces some T3 directly), then they are certainly not going to convert enough T3 from T4 only. Traditional medicine assumes that preparations like Synthroid which are T4 only converts peripherally in the body to T3 in fairly standard amounts and at fairly standard rates. Unfortunately, clinical experience shows this is not true for the majority of patients. Consistent measuring of both free T3 and free T4 blood levels in hypothyroid patients who are on T4 only therapy will very rapidly dispel this myth. A certain percentage of hypothyroid patients do convert enough T4 to T3 at a sufficient rate for T4 treatment to be adequate as a source of T3; but a substantial proportion of patients require some combination of both exogenous T3 and T4.


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