Thyroid UK

FREE T3 Result

Just got my Free T3 result from Medicheck which states 'within normal range'

Be grateful of some feedback on my results please. Does anyone think that a small amount of T3 might help to get me feeling back to normal? I'm almost housebound with my symptoms ie fatigue, weakness etc.

Free T3 3.66 pmo1/L 3.10-6.80


Serum TSH level 0.37 miu/L [0.27 - 4.2]

Serum free T4 level 22.1 pmol/L [12 - 22]

Serum folate level > 20 ng/ml [3.9 - 26.8]

Serum ferritin level 118 ng/ml

Serum vitamin B12 level 581 ng/L [197 - 771]

Serum 25-Hydroxy vitamin D3 level 60.9 nmol/L

Serum cortisol level 492 nmol/L


5 Replies

A few questions needed before any response. What dose of levothyroxine were you taking when you did the blood tests with the doctor. What dose of levothyroxine were you taking when you did the private blood test for T3? Have you got thyroid antibodies and if so what were your thyroid antibodies results for TPO and TgAb?

1 like

Sorry forgot to add my dosage of Levothyroxine. I have been on 100mcg for several years now. Regarding Thyroid antibodies they have never been tested as far as I know.


Although your FT3 is low with your new test, you really need FT4 and FT3 tested at the same time to know if you have a conversion problem, doing them 3 months apart and, probably, at a different time of the day, isn't going to tell you anything.

With Medichecks a lone FT3 test costs £29, a Thyroid Monitoring which tests TSH, FT4 and FT3 costs £39. Not sure why you didn't do the Thyroid Monitoring test.

Two weeks ago you asked which test to do and I replied

If you're having FT3 tested, then do FT4 at the same time as that will tell you whether your T4 to T3 conversion is good or not.


Thanks for replying. Not understanding all these different tests I can see I got it wrong. Case of I should have listened!!



You really need to test TSH, FT4 and FT3 together to determine whether conversion is good or poor but FT3 3.66 is low in range so you probably will benefit from adding some T3 to your current Levothyroxine dose.

TSH was low normal in May and FT4 mildly over range.

Folate, ferritin, vitamin B12 were all good.

VitD 60.9 was suboptimal but should have increased if you've been able to get sun on your face and arms during the summer. If not, I would supplement 5,000iu D3 daily x 6 weeks and then reduce to 5,000iu alternate days and retest in April. VitD should be taken 4 hours away from Levothyroxine.


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