TSH too low? : Hi I’m waiting for my T4 results... - Thyroid UK

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TSH too low?


Hi I’m waiting for my T4 results but I have my TSH results are 0.6 range 0.3 to 6. I’m currently taking 125mcgs of levo. Is the TSH too low?

12 Replies

You need to have FT4 and FT3 test results and the NHS rarely tests the latter. Your TSH is in the range so not too low.

Newbyface in reply to Treepie

I know but as these tests aren’t available I can only go off what I have


Treepie in reply to Newbyface

If you can afford it Blue Horizon and Medichecks do comprehensive thyroid tests.

But the TSH test is not useful, so ...


I think it's fine. Some need their TSH suppressed to feel well. It's the doctors who worry that we'll have a heart attack or osteo if TSH is too low but people who've had thyroid cancer have to have a suppressed TSH.


No, it's within range 0.3 - 6.0 so it's not too low.

For what this is worth: Don't worry about your low TSH, mine has been .002 or less for 13 years now and I have no heart problems nor significant osteoporosis - I am old so a little bit of the latter might be expected. Diagnosis by TSH is OK over a certain range from about 2 and up to a high level (I am not sure what the upper limit is, let's say about 100). Over a wide range the relationship is linear or at least a linear polynomial, and the current "mythology" holds true. At very high and very low levels however the relationship is not linear and conclusions cannot be made about overall status of the endocrine system as it relates to the thyroid. In other words, as others have said above, don't worry about low TSH!


How do you feel? Do you still have symptoms?

Just TSH tells nothing. You may have low FT4 or high FT4 and low FT3

If your vitamin levels are too low you can still feel very unwell. Blood tests can look "normal" but you can have very low conversion of T4 to T3

Ask GP to test vitamin D, folate, ferritin and B12

Do you have Hashimoto's? Confirmed by high thyroid antibodies. If not been tested ask that they are

For full evaluation you ideally need TSH, FT4, FT3, TT4, TPO and TG antibodies, plus vitamin D, folate, ferritin and B12 tested

See if you can get full thyroid and vitamin testing from GP. Unlikely to get FT3, but it's essential

Private tests are available


Medichecks Thyroid plus ultra vitamin or Blue Horizon Thyroid plus eleven are the most popular choice. DIY finger prick test or option to pay extra for private blood draw. Both companies often have money off offers.

All thyroid tests should be done as early as possible in morning and fasting and don't take Levo in the 24 hours prior to test, delay and take straight after. This gives highest TSH, lowest FT4 and most consistent results

Link about antibodies


Link about thyroid blood tests


Print this list of symptoms off, tick all that apply and take to GP


See Box 1. Towards end of article

Some possible causes of persistent symptoms in euthyroid patients on L-T4

You will see low vitamin D, folate, ferritin and B12 listed


Newbyface in reply to SlowDragon

Thankyou for all your advice x

Your TSH is fine. Anyway, TSH is largely irrelevant when on meds. If you have Hashis, you might need it even lower. The important thing is to keep your free T4 and free T3 in the top quarters of their ranges - that's what defines how you feel

Thanks for the advice. I have noticed that since I upped my levo my hair has started to fall out and I thought it was due to the TSH levels. Any advice?

Lot of things cause hair loss, but TSH is not one of them. Free t4 or free T3 too high or too low, ferritin/iron too low, B vitamin deficiency, too much testosterone aromatising to DHT (ie sex hormone imbalance) to name a few. You need to get a full thyroid panel done and get ferritin, B12, folate and vitamin d tested. TSH is NOT a thyroid hormone and doesn't always do what we have been told it does - it definitely doesn't tell you on its own whether you are over or undermedicated. Doctors may tell you it does, as it a very cheap test, but it does not.

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