I was diagnosed with Graves disease back in 2002 and was on methimazole for a year and a half before going into remission. Because of this, I wanted to make sure it did not come back during my pregnancy. I had my doctor test my TSH levels at 15 weeks and they came back at 0.013, very low. She proceeded to test both free T4 (16 weeks) and total T4 (17 weeks). Total was around 16, slightly high, but free T4 was perfectly normal. My OB says that because free T4 was normal that I shouldn't worry, but that she will continue to test periodically. I'm concerned that my TSH was so low in the first place, I didn't think that hCG could drop it that low. Also, my pulse is elevated again, the first symptom I developed back when I was first diagnosed with Graves. Should I be concerned that the Graves is back and start PTU, or is this a normal thing to happen to one with previous Graves who is pregnant?
Thanks.