Thyroid UK
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Whens the best time to take TSH and thyroid test?

I usually do my labs around 7 am before work at a location close to my house, The last test was 3.93, but when I took my last lab 3 weeks ago it was at noon and was 2.31. Does time make a difference in the thyroid tests. My ultrasound shows enlarged thyroid. and antibodies but TSH in Normal range. Going back in 3 months and also having t4 and T3 tested.

5 Replies

rjerome812 Yes, timing makes a difference. If you want a high TSH to avoid a reduction in dose of Levo or when looking for an increase, or for diagnosis of Hypothyroidism, then arrange the blood draw as early as possible in the morning, fast overnight and leave off Levo for 24 hours. TSH lowers after food and later in the day.

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Im not on medication yet. But i will go early in the morning. Thank you



The graph in this link shows how TSH fluctuates throughout the day


Yes TSH is highest very early morning

hence its utterly vital any test is always early .fasting.drinking only water and never take thyroid meds in the 24 hours before

But are you not being treated bcos no way should a correctly medicated hypothyroid patient havr a TSH like that


Yes, for all the reasons explained above. Early morning before breakfast and before medication is the best. If you have to travel a long way for the test (which I do), be sure to be consistent. Don't get one locally at 8:00am then the next at another lab, further away, at noon - even if both are before brekkers and meds.

It takes me three hours to get to my blood draw lab and I do not have breakfast before the draw nor do I take my NDT. It is quite an ordeal because I absolutely need my breakfast before I can string two sentences together. I live in a remote place in California and all of my local labs closed down (well, one is still open close to a heavy duty prison 60 miles away but that is quite creepy!).


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