Thyroid UK
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T3 and TSH levels

I am 39 and trying to conceive. I have an underactive thyroid and following a TSH of 2.75 (T4 of 17) a couple of months ago, my dose was increased from 75 mcg to 100 mcg.

My new test is showing TSH 0.19 (range of 0.4 to 5.50miu/L).

T3 is 3.7 (range of 3.10 to 6.80 pmoL)

T4 of 19.4 (range of 12.00 to 22.00 pmoL)

So now the GP is worried TSH is too low and has ordered another test in a month in case it drops further.

Strangely I am still showing some hypo symptoms including tiredness, coldness and dry skin near my eyes.


As for the others, two months ago when I did last my result I was showing the following levels (but after advice here I've upped my dose further in the past two to get Vit D and ferritin optimal). Not had blood test since.

Ferritin 44 ug (range 13 to 150)

B12 1382 ng (range 197 to 771)

Vit D 69.6 nmo (range 50.0 to 120.0) Note I am Asian with mid brown skin.

My cholesterol is 6 (I have a lipid appointment scheduled but suspect this is linked to the thyroid issues)!

Any thoughts?


7 Replies

For vitamins B12 and D plus iron you need to better than in just in range so I suggest you edit your post and put those test results with their ranges for each of them

For example someone with a ferritin level of 10 and 75 are both in the range 7-150 yet the person with the ferritin with level of 10 will be feeling exhausted, cold, breathlessness and have difficulty walking down the street let alone exercising.


Oh and you FT3 is too low it should be around 5.2 so it means you aren't converting T4 to T3. (The TSH is irrelevant as you are on thyroid hormone replacement. ) Do you have autoimmune thyroid disease?



Many only function well with a suppressed TSH but unfortunately doctors like to keep us within range.

Although you have had a med dose increase, your T3 levels (active hormone) is still under range and would account for your hypothyroid symptoms.

Optimising iron and nutrients and reducing possible elevated thyroid antibodies (if you have Hashi) will help T4 convert to T3. Alternatively you may need to add a little T3 meds.

It is imperative to keep TSH low and thyroid hormones optimal as low thyroid hormone can lead to fertility issues by disrupting of ovulation (when the egg is released from the ovary and ready for fertilisation) as more thyrotropin releasing hormone (TRH) and thyroid stimulating hormone (THS) is secreted in response but also prolactin that can interfere with ovulation.

Also, it is known that the need for thyroid hormone increases in the early part of pregnancy due to the increased oestrogen levels of early pregnancy. You will be your baby's only source of source of thyroid hormones as your baby's thyroid gland isn't fully functional until after 12 weeks of pregnancy. If you don't have sufficient thyroid hormones, you are at an increased risk of miscarriage, and your baby is at increased risk of developmental problems.


Ensure your doctor is familiar with NICE guidelines.


There's nothing wrong with your TSH. It is not a thyroid hormone it is from the Pituitary Gland and rises when your thyroid gland is struggling. They believe in rumours, i.e. if TSH is too low we will get a heart attack or osteoporis but this isn't true. They are poorly trained.

Levothyroxine is T4 only. It should convert to sufficient T3. T3 is the only active hormone required in all of our receptor cells to enable our body to function normally.

All doctors and Endocrinologists seem to be so badly trained in the importance of the thyroid gland, considering it has to run our whole metabolism and our brain contains the most T3 receptor cells and heart needs optimum etc etc.

Your T3 is at the bottom of the range and should be nearer 6. If you can afford a private blood test we have recommended labs which will do al of them for you or you can do less but the Free T3 and Free T4 are most important and I'll give you a link to read about both.

I shall also give you other links:

Many women can have miscarriages if they aren't looked after well. Others who have more experience than me will respond.

The aim of thyroid hormone replacement is to relieve all clinical symptoms. Several research teams have shown that a T3/T4 combination is beneficial for many patients.

Blood tests should be at the very earliest, fasting (you can drink water) and allow a gap of 24 hours between your last dose of hormones and the test and take afterwards.

You need TSH, T4, T3, Free T4, Free T3 and thyroid antibodies.

GP should test B12, Vit D, iron, ferritin and folate.

1 like

Your doctor is uneducated in thyroid matters. I was going to write "is a pillock" but maybe he knows a lot about other medical conditions...

Don't let him reduce your dose. You probably need a raise, not a reduction.


Haha pillock!!! 😂😂


Thank you all, I suspected it was something to do with T3 rather than TSH (and in fact, it's only because I insisted on having a T3 test this time that I got that result).

I don't know if I have Hashi or an autoinmmune disease - how do I get diagnosed for this?

I do have private healthcare and in fact it was that doctor who told this GP that i needed to be under 2.5 in a letter. However, my private healthcare provider doesn't feel that this issue is necessary and therefore won't pay out for more endocronologist appointments.

I'll wait and have the blood test in a month (I'm on holiday for a couple of weeks anyway and then go back to see if I can get a referral to a private specialist after that) we'll have been trying to conceive for over 6 months by then too. I always fast, wait 24 hours etc when I have a blood test so that has been taken into account.

As for the others, two months ago I was showing the following (but after advice here I've upped my dose further to get it optimal)

Ferritin 44 ug (range 13 to 150)

B12 1382 ng (range 197 to 771)

Vit D 69.6 nmo (range 50.0 to 120.0) Note I am Asian with mid brown skin.

My cholesterol is 6 (I have a lipid appointment scheduled but suspect this is linked to the thyroid issues)!

Thanks so much


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