Dear Ask The Doctor: Hi, I am desperate. Please someone help me. I moved to Canada because my husband is from Canada. And now we are pregnant with our first baby. I am 5 weeks pregnant and my TSH level is 3.6. I know that the new scale that the US is using is from 0.3 - 3 but Canada does not agree with it. They still use the 0.3 - 5 scale, which is the old one and not necessarily the most accurate one. So they are telling me that I do not need to be on medication, that my TSH level is fine like this and that it will not affect the baby at all. I should also tell you that a year ago my TSH had been at 4.6 and that I was put on synthroid for a few months but then taken off because it regulated it self. I also did a TSH level before getting pregnant like 7 weeks ago and it was at 3 exactly so it has gone up to 3.6 now that I am pregnant. I need help knowing if I should trust the Canada scale and the doctors here or if I should consult my own doctors in the USA. I am extremely worried, please please please help. Thank you so much to anyone who answers. Sincerely, Marina.
Dear Patient: The normal reference range of Thyroid Stimulating Hormone (TSH) is 0.4 – 5.0 mIU/L, however laboratories vary slightly in their reference ranges. You do not mention any symptoms you have so therefore I assume you do not have any. Thyroid function tests may be altered in pregnancy, total T4 especially can be elevated due to increased thyroid binding globulin levels. The TSH level you mention is normal, but this is not the complete set of thyroid function tests; therefore if you are asymptomatic I don’t believe you need any treatment. Consult your family doctor for further advice.