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Thyroid UK
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Transient low tsh result

I am female in my forties,

Over the past 10 years when having my thyroid tests done they were all within range. Only a couple a times over the last 10 years my TSH comes back slightly low. The last time it was slightly low was 2013, then now.

I am now seeing an endo that will recheck me in 3 months. I have had antibodies come back normal and a thyroid scan which was also normal. Any thoughts on why I can go so long with normal TSH then a slightly low result would be appreciated.

Below are my latest results.


Thyroid Function

TSH A 0.28 Ref range 0.32-5.04 mU/L

T4 Free 14.4 Ref range 10.6-19.7 pmol/L

T3 Free 4.71 Ref range 3.00-5.90 pmol/L

7 Replies

Are the tests always done at the same time of day, and fasting? TSH is highest early in the morning, and drops throughout the day. It also drops after eating.

One negative TPOab test does not completely rule out Hashi's, because antibodies fluctuate. Also, you could have high TgAB, which would also indicate Hashi's. Plus - to make things even more complicated - some people with Hashi's never develop high antibodies.


Hi greygoose,

No the tests haven't been done at the same time. Usually between 8 am and noon. Next time I will go earlier in the morning while fasted. Maybe that will make a difference.

I have had 13 TSH and Free t3 and free t4 tests done over the years. Only my TSH comes slightly under the level. Never T3 0R T4.

Out of the 13 times I have been tested the TSH has only been abnormally low 3 times.


That would be a good idea. If the tests aren't done under the same circumstances each time, you can't really compare them. :)


Hi, thanks. Maybe next time when getting retested I should go at 8am fasted?


Yes, that would be better. :)

1 like

Could I just check - are you on any thyroid hormone replacement?


Sorry, No. I never have been. Not diagnosed with anything either.


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