Hypothyroid and TSH dropped - anyone else?

[Hopeful1904]

Hi there, I'm hypothyroid and have been for 5years or so (since I was 24/25). I used to be hyperthyroid before this when I was in my late teens. That went away after 4years and I was stable for about 3years before going hypo.

When I first started TTC, I had a blood test and my TSH was 0.74 and I was on 75mcg a day. 3cycles later I found out I was pregnant. I had my bloods tested at 4 and a half weeks and my TSH was 2.39 which according to the doctor was normal. I chased this up with the midwife and got an app with an endo in the maternity dept. I had another blood test at just shy of 7weeks and my endo told my TSH has dropped to 1.47 which he said was very unusual. In fact he said that's not normal. I kind of nervously joked "I am still pregnant right," to which he and the nurse playfully laughed and then brushed off. He put me up to 100mcg anyway to be on the safe side and said I need to see him again in 6weeks. I won't have my 12week scan until 21st Jan but I'm now concerned as to why it's dropped. I'd understand if my meds had changed before this but they hadn't.

I had to do a urine sample before I met the endo and the nurse took it for testing. Would she have checked that I was still pregnant? She didn't say anything was wrong with it. I'm paranoid that the baby's stopped growing and that's why my TSH has dropped. I should have asked more questions at the time but they seemed so unworried. I still have pregnancy symptoms. I feel a bit nauseous if I don't eat regularly and boobs are sore, though I've heard that you can still feel symptoms even if it has stopped growing.

Has anybody with hypo had their TSH drop all by itself in the first trimester?

Thanks xx

What caused your hyperthyroidism? Could it be possible your thyroid is going hyper again?

Hi Hopeful,
Were the tests that you are comparing all done at the same time of day? TSH secretion is higher at night if I remember rightly, and decreases over the course of the day to a low point in the afternoon. If your last test was done later in the day then it might well be expected to be lower. Also, did you have all the tests before you'd taken your thyroxine for the day? I think that TSH goes down once the thyroxine is absorbed into your bloodstream. I've seen lots of suggestions that thyroid function tests should always be done as early as possible in the morning, before eating and before taking thyroxine. Did the lab measure your free T4 too so you can see where that sits within the range?
Hope this is reassuring. Is there an option to pay for an early scan privately to hopefully put your mind at rest? x

Initially they told me Graves' disease back when I was 19, but then when I developed an underactive thyroid in my mid twenties, the new doc when through my notes and said the tests for graves came back negative and I never had it. They have never said what did. Very annoying.

Hi Kettleson,

That's a good point about time of day, my first bloods were taken at 8.30 about an hour and a half after I took my levothyroxine, whereas the second set weren't taken until 3pm and I would have taken my tabs at 7am. Perhaps that's it. I hope so. Unfortunately I csnt have an early test as I'm flying to the states tomorrow to visit family for Christmas (booked before I fell pregnant). I love going on holiday but I've never wished the time to go fast before. I just want it to hurry up and get to 12weeks. X

Your TSH should be low when pregnant, under 2, and your meds should be increased to compensate for the baby in the first trimester.