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!
I hate when you feel like you are onto a good theory and your doctors poo-poo it!
ReplyDeleteFor the record, I felt like I started regulating my body temperature better too after I started treating my thyroid!
You explained that in non-scientific terms very well. And I agree... listen to your body, your temps, your instincts!
ReplyDeleteI definitely agree that you need to listen to your instincts. I have not felt any increased body temp myself until the past few days, notice I still get chilly as easily as usual, etc, but then our a/c was out at work and I discovered that I do NOT handle increased temps as well as I usually do at all. So I guess my basal temp has definitely increased! (I don't usually check, because when I tried it for the first time a year or so ago, I was also on strict diet and training for a half marathon, and that screwed everything up so much that I vowed to never check again!)
ReplyDeleteTwo things - please please PLEASE make them get a FREE t3 and FREE T4 on you next time. Total values are of NO use in pregnancy, because of pregnancy causes an increase in protein binding globulins that bind both T3 and T4 - and what's bound is inactive, but is measured when you get a total T3 and T4. It's impossible to interpret total values in a pregnant woman, and yet most OBs continue to get total values because all they remember from medical school is to get the totals, either because frees didn't exist at the time, or because early in the history of these labs the tests for the free values were wildly inaccurate (which has not been the case for years). You need to insist on this - tell them you have a friend who in an endocrinologist and that I'm reviewing your labs, and then tell them exactly what I said. You'd be amazed how much more responsive some docs can be when they know an outside doctor is involved.
Second, be careful with selenium. It is very easy to get too much, and it can be highly toxic. I've read case reports of people getting liver disease from selenium because they ate too many walnuts (a selenium rich food). It's reasonable to supplement now for the reasons you gave, just be careful!
@ Shannon: I've tried to get them (UCSD endocrinology) to test free T3 and T4. The argument they gave me against it used some of the same facts you presented (that protein binding globulins increase in pregnancy) only they concluded that because of that, the free levels will be 'too low' and hence might be misleading. But what they did not factor in is the bound form is inactive (!!!!)
ReplyDeleteThe other thing that drives me mad about them is that they refuse to test T3 (in any form)! They are supplementing with T4, so they'll test T4 and be done with it. Nevermind that T3 is the big player and rates of conversion depend on too many variables. IDIOTS.
Also I wonder if they have managed to figure this one out- what are TSH levels reflective more on? T3 or T4?
I'm going to go back and tell them what you said
Are there articles talking about this? If I can throw literature at their heads it might also help them see reason faster. And also, are the reference ranges for free T3/t4 different in pregnancy? If so, that information would be useful cause I have a feeling they have no idea how to interpret, never having done it before.
About the selenium, yes, I am worried about that as well. My supplement has 100 mcg of selinomethionine and my prenatal supplies 50 mcg. Papers that discuss selenium supplementation in pregnancy talk about 200 mcg doses/day, so according to THAT, I'm ok. But its still amateur hour, but then, my docs seem to be amateurs too, so AARGH!
There was a study last year that showed that free T4 levels do drop in pregnant women (without thyroid dysfunction) in the second and third trimester, and I do usually accept a free T4 at the low end or even just below normal as ok, as long as the TSH is ok (ie, < 2.5). My problem with doing just a total T4 is that you don't know exactly how much is bound up with proteins. If they're going to insist on doing a total T4, then they have to do a free T4 index along with it, otherwise they can't really comfortably go with just a total T4. Here's the only reference I can find with normal free T4 values in pregnancy, though those normals really do depend on what lab you're using: http://www.obfocus.com/high-risk/Thyroidtests.htm
ReplyDeleteTo the best of my knowledge, TSH reflects both T3 and T4 equally.
This comment has been removed by the author.
ReplyDeleteThanks Shannon, I'll talk to them next week.
ReplyDeleteIts very interesting that TSH is supposed to get suppressed in the first trimester. In my last pregnancy, it rose up in the first trimester, and even in this one (though its been super suppressed compared to my pre-synthyroid days) it went up from 0.4 to 0.9 between 4 weeks and 6 weeks of pregnancy. I thought that just meant that thyroid hormone requirement was increasing (logical), but it seems like most women have a negative feedback (with sufficiently increased T3/T4) that suppresses it, but I have not reached that point yet.
Jay,.. I think you should definitely tell your doctors that you have doctor friends (Shannon and I) and we encourage free T3 and T4 testings.. It always help to tell doctors that you have friends who are physicians.. trust me on this one. It's just professional courtesy.
ReplyDeleteI don't know much about thyroid stuff, but when you have your baby, I will can answer all the pediatric questions.
It must be so frustrating to have to go through all this on top of just regular pregnancy worry. Take care.
ReplyDeleteI'm way late on this one, but have you considered switching to Nature Throid or Armour instead of Synthroid? They are desiccated bovine thyroid and give you both T3 and T4 (as well as the others - it's the full complement of thyroid hormones). I had normal TSH, but low T4 and abysmal T3, so I had a definite conversion problem. My naturopath did say that in people without a conversation problem, whose T4 is low but their T3 is normal, the Nature Throid or Armous can cause them to get too much T3. So, yeah, testing free T3 and T4 is what you need. I find my naturopath to be so much more helpful and knowledgeable about those kinds of things than a typical MD.
ReplyDelete