Trending
Dear Dr. Roach: I have low thyroid levels. My blood tests say that the levels are OK, but I still have all the symptoms. I received biological hormones, which helped a lot, but yams bind to the levothyroxine pills. -- S.P.
Answer: The symptoms of low thyroid levels can be very nonspecific. Fatigue or weakness, intolerance of cold temperatures, and weight gain are common, but many conditions (anemia is a big one) can cause these as well.
In my general internal medicine practice, I see a lot of normal thyroid tests because so many conditions can resemble low thyroid levels. If the thyroid tests are normal, though, then it's very unlikely that the thyroid is the cause of the symptoms.
There are a handful of exceptions, such as people who have normal T4 levels (T4, or thyroxine, is the mostly inactive precursor to T3, which is the most active form of the hormone) but are unable to convert T4 to T3, leading to symptoms of hypothyroidism with normal T4 levels. Unless the doctor checks their T3 levels, they can miss this diagnosis, which is uncommon but not rare.
TSH, a hormone produced in the pituitary, can sometimes be mildly or not at all elevated because the normal T4 levels fool the pituitary into "thinking" that the thyroid levels are normal. The correct treatment is T3, usually given with T4, but T3 must be given twice daily. I don't recommend "natural" hormones made from pig thyroids because they do not contain the correct ratio of T3 to T4. There are precisely dosed bioidentical T3 and T4 preparations available.
I do see that yams (technically, sweet potatoes) can block the absorption of thyroid hormones, but this is true only when eaten raw and in large quantities. So, most people do not need to worry about this.
In my opinion, you should get your T3, T4 and TSH levels checked. But if they are normal, you need to find out what else might be causing your symptoms.
Readers may email questions to ToYourGoodHealth@med.cornell.edu.