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Your thyroid and you: A Q&A with Dr. Elizabeth Pearce

Elizabeth N. Pearce, M.D., M.Sc.
Boston University School of Medicine
  • This interview is part one in a two part Q&A article for

An Associate Professor of Medicine at Boston University School of Medicine, Dr. Elizabeth Pearce received her medical degree from Harvard Medical School and a Master of Science in Epidemiology from Boston University School of Public Health.

When it comes to the thyroid, Dr. Pearce’s interests include the sufficiency of dietary iodine in the United States, thyroid function in pregnancy and lactation, the thyroid effects of environmental perchlorate exposure and other potential endocrine disruptors, and the cardiovascular effects of subclinical thyroid dysfunction.

Dr. Pearce recently took some time from her work at Boston University School of Medicine to talk further about our thyroid health, and to discuss some of her current interests in this area of medicine.

Q: Here we are, almost four months into 2012. Many people who made New Year’s resolutions are either sticking with it, they aren’t sticking with it, or they are feeling frustrated because they might not be losing weight, and may be feeling exhausted. What do you want to say to those who are in this position, and have no understanding of their thyroid health? Could difficulty with shedding those extra 10-20 pounds and feeling exhausted have to do with an underactive thyroid?
A: It could be thyroid related. Symptoms of hypothyroidism are very non specific – constipation, feeling cold, weight gain, fatigue, but all of these can occur for 100 different reasons. These symptoms may or may not be related to your thyroid, but the easiest thing to do if there is any suspicion is to have the TSH checked through a simple blood test.

Q: I’ve read that the normal range for the Thyroid Stimulating Hormone (TSH) blood test is .5 to 4.5/5.0. And then I’ve read that in some cases it is a 0.3 to 3.0 range. Do you have any recommendations as far as understanding which range seems most appropriate and accurate?
A: Keep in mind there are different TSH blood tests made by different manufacturers which have slightly different ranges. The controversy has been around the upper limit of the TSH, and how to define mild hypothyroidism. Some of the best information we have is from the National Health and Nutrition Examination surveys.

In these national surveys, thyroid function and thyroid antibodies have been measured in a large population. Some investigators have suggested that if you use these national data and eliminate people who have positive thyroid antibodies or family histories of thyroid disease, then the upper limit of TSH is lowered -- part of the controversy is how do we determine which individuals truly have normal thyroid function in defining reference ranges.

Other groups have said we know that normal TSH ranges may change with aging. And in pregnancy the interpretation of TSH is very different. It’s critical in pregnancy because we think even mild hypothyroidism can adversely affect a pregnancy and the fetus. In normal pregnancy thyroid function changes from one trimester to the next, so interpretation of thyroid function tests in pregnancy is not the same as for non-pregnant individuals.

The American Thyroid Association published new guidelines in October 2011 for pregnancy.

Come back here Monday, March 26 to learn more about the important role the thyroid plays in your health in part two of our conversation Your Thyroid and You.


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