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Thyroid UK
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free t4 level

need help pls. I've recently had a series of blood tests done and my t4 level is high at 33, tsh and t3 within normal range. however 6 weeks ago my t4 level was normal at 14.9. how can this change so quickly? GP wants to start me on Carbimazole but petrified of the side effects. surely I need to know why the dramatic increase in such a short space of time ?? Thanks

8 Replies

Have you had your antibodies tested?


I believe so........my whole screening was normal aside from my t4


Get full copies of all test results including ranges and post on here


It's no good just believing, you need to know.

Doctors will test antibodies, and then ignore them.

But, if your FT4 went high because you have Hashi's antibodies, then carbimazole is the wrong treatment.

On the other hand, if you have Grave's antibodies, it's the right treatment, which your doctor obviously believes.

But, very often they suspect something but don't test for it, just start the treatment.

However, if you did have Grave's, your FT3 should be high, as well as your FT4, and your TSH would be very low.

But, you say this isn't the case. Therefore carbimazole isn't the right treatment.

But, none of us can know without seeing the test results - including your doctor.

So, before starting any treatment, you need to get hold of your results.

1 like

It possibly is interference in the FT4 test from short-term antibodies in your blood that can come and go in some people, esp those on T4. FT4 only going up so quickly with no TSH or T3 effect suggests a test problem rather than hyperthyroidism.

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so bit of background everyone I'm brand new to this diagnosis so freaking me out some what. I suffer from anxiety anyway so I'm not in a good place. firstly I had a UTI so was on cefalexin...then I developed a blistering rash on my palms and soles of feet for which the GP couldn't identify an accurate diagnosis so was given Fexofanidine which I'm still taking. I've heard stress and infections can cause your thyroid results to go a bit wayward.....Im thinking I should hold fire on Carbimazole for a while in case it's a false positive. It's proving somewhat difficult to obtain my results...receptionist can only see my TSH not my t3 or t4! my Tsh is 0.37 ( 0.35-5.50 ) and my t4 is 33 (12.0-22.0) that's all I know at the moment.....got an appt with the GP on Monday xx


You are entitled to full test results

You need to know especially which antibodies were tested and the results

Anxiety is a common symptom of Graves and Hashimotos

1 like

I'm doing my best to get them! I work in a GP practice ironically but not where I'm registered.....


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