This post is mostly reads like a cross between a science lesson and science fiction. Most of you will be bored senseless, but for any of you with thyroid issues, this might be a little informative. Anyway, its cathartic to just put it all out here, so here goes. If you attempt to follow this and your head hits your keyboard as you fall asleep reading, I apologize!
Your body temperatures are controlled by hormones. Estrogen is a hormone that pushes your basal body temperatures down, while progesterone elevates it. These are not the only players, the other big ones are the thyroid hormones. This is scientific fact, known hopefully by everybody who graduates from med school (yeah, I'm still in my annoyed with docs funk. RE is spared though, he is the one person who actually attempted to LISTEN to me).
During my first pregnancy, the thing that struck me was that I was so cold, so often. 2 days after I got my positive pregnancy tests, my temperatures nosedived by a DEGREE. For somebody whose BBTs run like a precision clock, this was huge. My progesterone, the hormone you would think was responsible for this, was utterly normal. My temperatures stayed low my entire first pregnancy, and so many times I'd be cold to my bones. I told my doctors this. They shrugged, said 'temperatures are utterly erratic in pregnancy, don't you worry your little head about it'. Did ANY of them stop to think, oh gee, thyroid hormone requirements go up in pregnancy, maybe this girl's temperatures nosedived because her body needed more hormone because her body was cooking a baby and this gobbles up thyroid hormone (scientific fact). No. Temperatures are an irrelevant, its not in the handbook, so why bother even throwing it in the mix?
According to the tests, I was 'euthyroid' in my last pregnancy. Which meant my thyroid hormones were in 'normal' range. But its now known that for women with anti-thyroid antibodies, simply being 'euthyroid' is not enough. If your baby is not getting enough thyroid hormone, things can go catastrophically wrong. Your TSH, the hormone measured to determine thyroid sufficiency, needs to be low in pregnancy. Mine was not (it was probably over the limit now considered the upper end of ideal for pregnancy). So, in retrospect, its logical that I was so cold the last pregnancy. This is utter TMI, but I had the worst case of holding it in as well, if you know what I mean. Like we are talking, 2-3 days. That is also a thyroid insufficiency symptom, thankfully one not at all present in this current pregnancy. Coincidence or the hormone I'm taking?
This time, since I've been on daily thyroid hormone supplements, I've been warm. Hot even. It's blissful. For the first time in years, I actually have warm feet! My BBTs have stayed up, my waking temps are usually 98.2, and during the day, its stays in the 99s. I know this because I randomly check temperatures multiple times a day. But even this has started to falter recently (I start feeling cold, check temps and find they have fallen by a DEGREE again). This is because (my theory) that with advancing pregnancy, my requirements are starting to rise. Its supply and demand really. If demand overcomes supply, then my body reflects it by dropping the body temps. I told my perinatologist about the falling temps. He was like, body temperatures, who cares about that? They mean nothing, don't worry your little amateur head about it. I literally wanted to hit him at that point, all of these guys are so by the book, they are like horses wearing blinders.
I think I have fixed the problem myself though. 2 things can be given to improve thyroid function. The first of course, is thyroid hormone. The second, is selenium. This is required for converting the less active thyroid hormone (which is what we get as the supplement synthyroid) into the super-active version (called T3). When I first started taking synthroid, I think it was just about how much I needed, or maybe a little more. At this point, I wisely stayed away from selenium in case it made me thyrotoxic. But as this pregnancy has progressed, I think my thyroid requirements have started to increase, and I think my body needs more of the very active form., T3. I have oodles of T4 (because I'm supplementing with that and my blood levels are sky high), but it may not be what is really needed, and there is probably a cap on the conversion rate of T4 to T3. So I've started selenium once a day. I first started it on the day I started freezing and my non-waking temperatures were around 98.4. Several hours later, my temps were back up to the 99s, and they have stayed that way. Today, they fell again (the freezing is an instant clue). Its really scary I tell you, because danger signal or not, I associate it with things going wrong. I took my selenium. I've been waiting and the temps are going back up, and I'm feeling hot again. Coincidence or not? Who knows.
I'm frustrated because I have to navigate this scary world by myself, and try to fix all of this amateur style. If I tell a doctor this (first they have to sit down to actually listen to you for 5 minutes and that may be too much to ask), they'll just shrug it away. If they don;t have a textbook answer for you, they will not even speculate and will just wave you away. And I really, really dislike that. Our body tells us a lot of things, and NOTHING is ever random. If something changes with your physiology, there is a reason for it. Sure the body is complex enough that you might never be able to know the mechanism behind it, but sometimes you can make an educated guess. Who knows, you might even be close to the mark!