Normal TSH & Free T4 but elevated Free T3?

[WK1010]

I asked this question in a comment of another post, but I'll post it here. What could cause this? I'm having more blood tests done soon. The value was at the upper limit 6.5 (reference range 3.5 - 6.5 pmol/L). This value has slowly increased from 4.9 then 5.9 and now 6.5 over a period of time.

[shaws Administrator]

Are you referring within the above to TSH or T4 or T3.

[WK1010 in reply to shaws]

I'm referring to T3.

[shaws Administrator]

I am sorry I am unable to respond. There's no history in your Profile at all but I've looked through a few past posts and I don't think you've yet been diagnosed with hypothyroidism?

[WK1010 in reply to shaws]

No, I haven't been diagnosed with thyroid issues. Thanks for trying though. I tried searching online but didn't really find anything.

[Clutter]

WK1010,

What were your FT4 and TSH levels and what period of time is it that your FT3 has been rising?

Your previous tests are a little odd because your TSH wasn't dropping when FT3 was rising and in Test 4 TSH 3.1 is quite high. If you were hyperthyroid we would expect to see suppressed TSH with high FT3.

TPOab below is negative but some people have negative TPOab with positive thyroglobulin antibodies (TGab) which would confirm Hashimoto's which can cause transient hyperthyroidism in the early days but I would still expect to see TSH suppressed.

Test no.1:

TSH: 1.5 reference value 0.50 - 4.6

Free T4: 20.4 reference value 11.0 - 23.0

Test no.2:

TSH: 1.6 reference value 0.20 - 4.0 mU/L

Free T4: 15.3 reference value 11.0 - 23.0 pmol/L

Free T3: 4.9 reference value 3.5 - 6.5 pmol/L

Anti-TPO: <34 reference value <100 kU/L

Test no.3:

TSH: 1.2 reference 0.50 - 4.6 mU/L

Free T4: 18.1 reference value 11.0 - 23.0 pmol/L

Free T3: 5.9 reference value 3.5 - 6.5

Anti-TPO: <34 reference value <100 kU/L

Test no.4:

TSH: 3.1 reference value 0.20 - 4.0 mU/L

Free T4: 17.2 reference value 11.0 - 23.0 pmol/L

I don't know, it looks normal to me.

[WK1010 in reply to Clutter]

Where I live a test called TSI is used instead of TGab. Should I request this test to be done? The results for the free t3 are from the past year I think till present, so the value has slowly risen in a year.

[Clutter in reply to WK1010]

Wk1010,

You can get private thyroid tests for TGab which is rarely tested in primary care. thyroiduk.org.uk/tuk/testin...

TSI (thyroid stimulating immunoglobulin) is a test for Graves disease. II think this is usually done in endocrinology rather than primary care and it probably won't be done until your FT3 is over range. It won't hurt to ask though.

thyroiduk.org.uk/tuk/about_...