Thyroid UK
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Thyroid results explained

Hi all, I was diagnosed with hypothyroidism 20+ years ago and put on levothyroxine 75mcg increasing to 125mcg, I have ticked along very nicely all this time and never questioned all the numbers T's etc when my doc read them out, so I've never understood what they all mean. Recently a different doc said my levels are too high and promptly reduced me to 100mcg then 75mcg, after 3 Months I feel dreadful tired lethargic and gained over a stone weight and I can sleep for England! I am also taking anti depressants and Asacol for UC . Can anyone explain basically what the numbers will mean when I go for my blood test this coming week so I can properly discuss my thyroid levels with my GP. Thankyou in advance.

3 Replies

Have you had a recent blood test or have you got one booked

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When you have your blood test have it done early, don't eat beforehand, but you can drink water, and make sure it's 24 hours since taking your levothyroxine. You can have breakfast and your levothyroxine after the early morning test. This will show a proper thyroid reading then of its function. The tsh will be at its highest and the doctor will be more likely to increase your levothyroxine. Unfortunately they go by the tsh result and not your symptoms because they are ignorant. You need your t4 and t3 done as well. Post your results on here and then members will be able to comment. If your doctor won't do the t4/t3 then you may need to go private as many of us have. You should have both thyroid antibodies done too to see if your thyroid disease is caused by hashimotos. The vitamin b12 and D as well as folate and ferritin would be a good indicator too of your symptoms as it is common for them to be low with thyroid disease.

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TSH is a pituitary hormone which responds to thyroid hormone levels (T4 and T3). When T4 and T3 are low TSH rises and when sufficient T4 and T3 is detected TSH falls.

The goal of Levothyroxine is to restore the patient to euthyroid status and for most that will be when TSH is between 0.35-1.0 with T4 in the upper quadrant of range but some patients will need lower or suppressed TSH and T4 over range to feel well. Read Treatment Options in

If you ask for a copy of your results with the ranges (figures in brackets after results) and post them in a new question members will advise whether you are optimally medicated.


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