Yes! I had it this pregnancy and in hindsight I think I had it with my last too. It was discovered when I was hospitalized for HG at around 8 weeks and they did more than the usual round of early-pregnancy blood tests. There is a lot of research linking severe NVP with low TSH, though jury's out on which causes which. Mine resolved on it's own around 20 weeks. I was supposed to be transferred to high risk but I begged my midwife to postpone the transfer and keep testing my hormone levels in hopes that they would return to normal. They did! I knew right away because suddenly in the 2nd trimester I was absolutely exhausted, right when most women are getting an energy boost. With both this pregnancy and my first, I never had the fatigue that people complain about in early pregnancy. Thankfully I didn't have the racing heart either (sorry to hear that you do) even though my TSH was almost non-existent. I did have severe vomiting with both pregnancies and it's possible that the nausea meds masked the other symptoms as they make me very sluggish.
The complications related to hyperthyroidism during pregnancy are scary but I think they are very rare if you are monitored closely. We had an extra close look at baby's heart at our 20 week ultrasound and all was fine. The late-term risks (thyroid storm, sudden eclampsia, preterm labour, thyroid problems in baby) disappear if your condition turns out to be transient, meaning it comes in early pregnancy only and then goes away before the end, which is most common.
I was not treated with any medications for the hyperthyroidism, though I took a cocktail of meds to try to control the vomiting, and from what I understand, hyperthyroidism is not usually treated during pregnancy but rather simply monitored closely. I think in general hyperthyroidism is very hard to treat. There is no magic bullet medication as there is with hypothyroidism so there may not be much your endo can do other than monitor your levels. Because of this, I was spared extra appointments with specialists - my midwife was able to do frequent blood tests herself and consulted bi-weekly by phone with an endo and a high risk ob familiar with the condition. I was so sick that I was very grateful not to have to drag myself all over the city for extra appointments, but I was still able to get the specialist's care through my midwife. I was days away from officially being transferred (no choice by law here) when tests showed all was suddenly normal again! Yippee! I've tested since then, though less frequently, and the problem has not returned. The endo said that once it is resolved, it always stays that way but I requested re-tests just to be sure.
On the flipside, a friend of mine developed hyperthyroidism during her first pregnancy and it did not go back to normal. She has had a second child since and both pregnancies and births went off without a hitch. No issues at all and both kids are totally healthy, without thyroid issues of their own. She however still suffers from the symptoms herself and is considering radiation treatment if dietary changes don't make a difference. Her endo says there are no drugs that will help her, only options are surgery or radiation, but her naturopath is very hopeful about other approaches - massive amounts of cabbage, etc, google and you'll find menus. I was too sick to try them but maybe you could.
I hope that your case isn't too severe and that all is back to normal for you soon. There were a few other people here who have been through similar and hopefully they'll chime in too. I'll check back to see if you have other questions or need support (or feel free to PM me).
