understanding thyroid blood tests

[Pinkflower15]

hello I have recently been to the gp about chest pains and was told I’m tachycardic which I have been for a few years, I had a ecg and the doctor done bloods and my thyroid bloods came back as

TSH- 0.11

T3- 6.6

T4- 11.1

I have a follow up doctors appointment next week my tsh says below reference limit and my t3 is above but t4 normal could this be causing my symptoms or is it nothing to worry about thank you

[PurpleNails Administrator]

Welcome to forum Pinkflower15

Do you have a diagnosed thyroid condition or is this a new investigation?

The Thyroid Stimulating Hormone is a pituitary hormone which signals the thyroid to work. When thyroid hormones (FT4 or FT3) rise, the TSH lowers & vice Vera. TSH can lag behind levels so is unreliable on it own.

Often autoimmune disease can cause the thyroid levels to fluctuate, this can be temporary with Hashimoto’s thyroiditis, and gradually function can lower (hypothyroid). Levels which are continuously high can be due to a different condition called Graves (hyperthyroid)

You’ll likely need to have some more test to see if your levels alter & ask for thyroid antibodies to be tested. TPO & TG antibodies can show if autoimmune is present. If levels remain high & drs suspect Graves it need to be conformed by TSI or TRab antibodies.

Always include lab range, as ranges vary between labs.

Your FT4 looks low by most ranges & FT3 which is more unusual.

High FT3 can cause fast heart rate. FT3 is the active thyroid hormone. Some feel less or un-affected by low / higher FT4.

[Pinkflower15 in reply to PurpleNails]

Hello thank you for your reply this is a new investigation I had my thyroid tested last year my tsh was low but not below the reference range so no other tests were ordered.

The reference ranges for where I am are

FT4; 7.7-15.1

FT3; 3.8-6.0

TSH; 0.38-5.3

I haven’t had any antibodies tested as the only standard test is tsh and if that comes back abnormal they test the t3/t4. This is all new to me I never suspected anything to be wrong with my thyroid as It’s not something I have ever looked into. It’s just the fast heart rate the doctors was investigating and I have seen the lab work come back on my nhs app my appointment in next week so I should find out more thank you