Hyperthyroidism In 12 Weeks Of Pregnancy

I feel super lethargic for the last few weeks plus occasional palpitations. Went for a check-up and the doctor pointed out a possibility of thyroid. We did a thorough blood test last week and it came back with Thyroid Stimulating Hormone (CMIA) of 0.01 (normal would be 0.35-4.55). I am super worried now but a friend doc who is majoring in endocrine says not to worry and to retake the blood test in week 16. Anyone has any experience with thyroid during pregnancy? What should I do? What should I avoid doing? This is my 4th pregnancy, by the way, and I'm 41 this year ?