T4 gone down from 67.8 to 14.3 but TSH is still... - Thyroid UK

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T4 gone down from 67.8 to 14.3 but TSH is still 0.01 what does this bit mean?

mrs-p profile image
8 Replies

i was prescribed carbimazole 5mg 3x a day which seems to have worked. what does the other bit mean? am going to see speciist end of month which is great as have had so much hair loss with wedding looming next sep. x

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mrs-p profile image
mrs-p
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helvella profile image
helvellaAdministratorThyroid UK

I don't know much about hyperthyroidism, but I think that it can take much longer for TSH to rise than for FT4 to fall. And I do mean possibly many months.

This is one of the difficulties in achieving good treatment.

Rod

mrs-p profile image
mrs-p

what is the TSH? its so hard to get any info from my doctors and this is really new to me.

marram profile image
marram in reply to mrs-p

TSH -Thyroid Stimulating Hormone - is released by the pituitary to stimulate they thyroid to produce T4 and T3. Most people with an overactive thyroid have a very low TSH because the pituitary stops production of TSH in an attempt to stop the thyroid producing too much T4 and T3. With Graves' there are antibodies which stimulate the thyroid regardless of what the pituitary does, this is Thyroid Stimulating Immunoglobulin, which as its name suggests, is a form of autoimmune response, and has the same effect on the thyroid as TSH, but is out of the control of the pituitary. In effect the TSI hijacks the function of the TSH and overstimulates the thyroid gland.

There is a possibility that when the carbimazole is slowing down the thyroid, there are still the TSI antibodies in the system, and there is some evidence that these antibodies can also stop the pituitary from producing TSH so that it remains suppressed. Sadly due to a hard drive failure on my computer I have lost all my links so I can't give you the link to this information.

I'm not sure if you have Graves' but it is the most common cause of overactive thyroid. Hashimoto's can cause the thyroid to become overactive temporarily, when the Hashi's antibodies first affect the thyroid and it suddenly releases all its stored thyroxine.

I do hope this makes sense!

I just found the article:

ncbi.nlm.nih.gov/pubmed/116...

helvella profile image
helvellaAdministratorThyroid UK in reply to marram

And the main Thyroid UK site has quite a bit:

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

Rod

lizmag profile image
lizmag in reply to marram

Gosh - this is the best and most succinct explanation of Graves that I've ever read. Thank you!

mrs-p profile image
mrs-p

thank you so much will have a good read of this. x

Joy333 profile image
Joy333

Hi, what strikes me is your t4 appears to have come down extremely rapidly from your previous post. Has your Gp cut back on the carbimazole with your levels being down? If not I would question this with your Gp at the start of the week as there is the possibility of becoming hypoT. X

greenginger profile image
greenginger

Hi.

T4 often comes down quite quickly on carbimazole but it can take a lot longer for your TSH levels to rise sometimes months.

I am guessing that once your T4 gets to around 12 that your TSH will have risen above 1.

You will probably be told that your TSH needs to be around 1 and your T4 around 20 but in my experience that isnt usually the case. Especially if you do have Graves. How long have you been on carbimazole?

I was on it for 2 years before going into remission last July. At that time my T4 was 13 and my TSH around 2.

.

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