Thyroid UK
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Low tsh and miscarriage?

I am looking for anyone whos had a healthy pregnancy with a low tsh.

I was diagnosed hypo about 5 years ago. I had such bad fatigue at the time I was mostly bed bound.

My results back then were free t4 7, tsh 11. Im not sure what my t3 was.

I was put on 100mcg levothyroxine and did feel an improvement but still suffered with bad fatigue and was.diagnosed with m.e

Then about a year ago I saw a different endo who suggested trying t3 as well. It helped enormously but I was very sensitive to it and we eventually settled on a dose of 75mcg t4 once a day and 2.5mcg t3 three times a day. I felt the best I had foryears. Not perfect but much better.

We started trying to concieve and fell right away. At 6 weeks the scan showed a healthy heartbeat.

Also at 6 weeks my endo stopped my t3 and increased my t4. My bloods were normal but he said t3 was too unstable to manage in pregnancy so its better just to have t4. I was not happy as I knowthe t3 would leave my system within daya but the t4 would take weeks to have effect so basically he was reducing my dose, til the t4 kicked in.

A few weeks later I miscarried and the scan showed the baby stopped growing around 7 weeks.

Could be unrelated. Anyway my lovely endo referred me to his professor saying he had more experience in pregnancy.

I went back on my original dose but when I saw the prof was told my tsh was way too low 0.02 so I had to reduce my dose, even though my free t4 was only 12 and t3 was 5.5. I was very cross as I know takimg t3 can supress tsh but did as I was.told. Reduced to 75t4 daily and 2.5 t3 twice daily.

I went on to have another miscarriage a few months later.

I was told my tsh was still way too low (still 0.02!) and it was possibly not helping the pregnancies. I asked if there was any link between low tsh and miscarriage and the prof said no but it was the only thing he could think of!

I tried cuttimg out the t3 but was so ill that its not an option.

So I am now on 50mcg t4 a day and 2.5 t3 twice a day and feel it isnot enough. I am having bloods done in dec (after beimg on this dose for three months) and not trying to.concieve til my dose is stable. Also having other miscarriage tests.

But really want to know if anyone has had a healthy pregnancy with a low tsh? As iI dont think it is the cause of my problems.

Thanks so much in.advance, any info on thyroid and pregnancy welcome!

8 Replies

I had a tsh of 0.01 my whole pregnancy and 6 months of breast feeding. I'm on t4 only. Sorry to hear about your struggles I hope u get well & pregnant soon. ❤


Im really relieved to hear that, I know everyones different but it is reassuring. So glad you had a healthy pregnancy regarding your thyroid xx

1 like

Hello Carrie97,

On reading your reply on this post, I think you could help me with my wife’s TSH report. We are planning to have a baby now, and when she took a health check we came to know that she has <0.01 TSH and normal ranges of T3 and T4. When we consulted the endocrinologist, he recommended us for Radioactive iodine uptake test to ensure whether it is thyrotoxicis. But the result showed normal. We are confused now. Is this a pregnancy sign? There are still 10 more days for her next Menstrual period. Can you help us with this



Hopefully it’s a positive pregnancy for you guys, once medicated correctly, feeling normal and good results my tsh was and has been 0.01 the last thing I’d be thinking about is radioactive iodine.



Thank you so much for your time and response. We have an appointment with the endo on Monday to show the reports of radioactive iodine uptake test. Is it better to wait for her period to miss and continue further diagnosis and treatment?


Sorry to hear about your miscarriages. Sad experience indeed! Maybe you should have your progesterone levels checked as low levels can result in miscarriage and premature birth. You can get a lot of good information at Progesterone also increases the sensitivity of the thyroid receptors, so you can utilize yor thyroid hormones better. Have you considered taking natural hormones instead of synthetic? I can recommend the book of dr. David Brownstein: 'The Miracle of Natural Hormones'


that's really interesting stuff, thank you so much, I'll check it out. My progesterone was low with the first pregnancy so they will give me extra next time but not sure if its natural or synthetic. Thanks again, really helpful xx


Hi, 0Lucy0

Low or normal TSH is compatible with hypothyroidism caused by pituitary failure (i.e. not by the thyroid gland itself). This makes me wonder if you might have other pituitary deficiencies, such as LH/FSH, which might be affecting your pregnancies. Also ACTH deficiency which can cause fatigue.

Many, many more people have pituitary dysfunction than are actually diagnosed see It can be caused not just by head injury (including mere concussion) but by autoimmune disease, genetic factors, cranial radiation, snakebite (!) and tiny benign pituitary tumours. So if you have any doubts, think of getting your pituitary function checked.

Evidence to show your endo . . .

Secondary hypothyroidism i.e. thyroid deficiency caused by the pituitary gland is not ruled out by normal TSH levels. Here's a quote from the PatientUK website: "Secondary hypothyroidism is suggested by low, within or mildly elevated TSH combined with a low FT4. Differentiating this from non-thyroidal illness can be difficult and clinical history, FT3 and sometimes anterior pituitary hormone tests are necessary."

Also a quote from Dayan CM Interpretation of Thyroid Function Tests, 2001, Lancet, 357, "If TSH alone is the first line test, what diagnoses will be missed? Sensitive TSH assays are widely used and financially justifiable as first-line screening tests. However, they can be misleading when: hypothyroidism is caused by pituitary disease (TSH is usually in the normal range)"


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