Slight Underactive Thyroid and IVF - Clarity required!

[KJM2013]

I've always tested slightly underactive on Thyroid blood tests. I believe that the normal range is a reading of say 3-5 and I register 5.25 (numbers may not be exact but you get the idea). I saw a specialist many years ago, who send they wouldn't even treat me with drugs until my reading was about 10 and that has been the end of it.

We had IVF and I am currently 18 weeks pregnant. As my reading was still out of range, I was given the lowest does of Thyroxine, during my treatment.

I have mentioned this at my booking appointment and again at my 16 week check up. Nobody was that bothered, although my midwife asked me to see a consultant at the hospital because I had IVF (no real reason why "they might just like to monitor you more closely", I am low risk on every other count-so that is another mystery) and that appointment isn't until 22 weeks.

Should I be demanding more tests with regard to my thyroid, or at this level it really isn't worth worrying about? Is this connected to my IVF? Any ideas or similar situations out there?

Hi KJM the short answer is yes you should be pushing for closer monitoring. It is v important that your thyroid hormones are kept within a healthy range during pregnancy, as if they are not it can affect the development of the baby. I'm not sure which figures you are quoting but the 'normal' range for TSH is 0.27-4.2 and for free T4 is 12.0-22.0. However in pregnancy these should be kept below 2 for TSH and above 16 for free T4.

If you have had a blood test recently I would ring up your GP and ask them to read you out the results (they will try to only say 'normal' but if you insist they should give you the actual figure). This way you will know what your levels are. Also, they should do a repeat blood test approx 4-6 weeks after you started or changed thyroxine dose, so that they can ascertain whether you are taking the correct amount. If they haven't done this yet then I would speak to your GP and ask for this to be done asap, rather than wait until your 22 week amount with the consultant.

FYI - I have had an underactive thyroid for ~3 years and take a low dose of thyroxine. I spoke to my doctor when i was trying to conceive and she said as soon as I fell pregnant I would be referred to the consultant endocrinologist for monitoring during the pregnancy. At my midwife booking appointment she also flagged that I would be referred to the endocrinologist and chased this up for me.

I had the first appointment yesterday (@ 15 weeks) and they said they would monitor my thyroid hormones every 4-6 weeks and would review my ultrasounds to check baby is developing normally.

Assuming your hormone levels are kept under control then everything should be fine.

PS doubt it has anything to do with IVF, but this is not something I have experience of.

Yes, you should. Most people need to increase their dose in pregnancy and some experts therefore recommend increasing your dosage as soon as pregnancy is confirmed, even before any blood test. Considering you were already borderline, you really should have been tested. www.ncbi.nlm.nih.gov/pubmed/15254282

I'm surprised they didn't treat you prior to pregnancy - I was classed as being just over the borderline of hypothyroidism whilst trying to conceive and they put me on levothyroxine (and metformin for the PCOS). Two months later, bam! Pregnant!

I was told I'd need to see an endocrinologist during my pregnancy - I saw them for the first time at my sixteen week appointment, and they've upped my doseage slightly due to my blood tests this month still being a bit higher than they'd like (3.7 tsh and 16.6 t4 this month, was 6.5 tsh back in December though, and that was after four months of treatment - not sure if early pregnancy had bumped it up though, I don't know what my original reading was before starting treatment in September!).

I'd give them another poke, if I were you.

And congratulations!