It is very important to correctly diagnose hypothyroidism. If a patient truly has hypothyroidism, they need to go on thyroid medicine; otherwise, their condition will worsen. On the other hand, if they do not have hypothyroidism and are treated with thyroid medicine, their own thyroid will shut down and it will be very hard to get off thyroid medicine. If you have a healthy gland, it is much better not to take thyroid medicine, as your own gland is able to respond much more dynamically to its needs and put out the right amount of thyroid hormone at the right time. However, if you have a sick gland then it is best to take exogenous thyroid medicine.
Dr. Friedman spends a lot of his time trying to decide who should and who should not go on thyroid medicine. The issue comes into play when the TSH, which goes up with hypothyroidism, is on the upper range of normal or even slightly elevated and the free T4 and free T3 are normal. The range of TSH is quite broad and it is controversial about what should be the upper limit of the normal range. Most people would say that if the TSH is above 7, the patient should go on thyroid medicine and if the TSH is probably below 3, the patient should not. However, there is a gray zone between 3 and 7 where it is unclear whether the patient should start thyroid medicine or not. Some of this has to do with symptoms, but the most important test to determine this is a test called the TPO antibody. TPO antibody stands for thyroid peroxidase antibody and this is a marker for Hashimoto hypothyroidism. By far, the most common reason for hypothyroidism is Hashimoto's and in fact, if you do not have the TPO antibody and you did not have prior surgery or radiation to the thyroid, it is unlikely that you truly have hypothyroidism.
Therefore, Dr. Friedman uses the TPO antibody to determine who with a high-normal TSH or slightly elevated TSH should go on thyroid medicine. If the TPO antibody is positive, most of the time Dr. Friedman will put the patient on thyroid medicine.