Some of the reasons that you do not feel well, or may even feel worse on thyroid hormone replacement, could be the following:
Your thyroid hormone dose may not be correct. This is certainly the case when your thyroid labs are outside the reference range. However, on certain occasions, even if the labs look normal, the dose may still need to be adjusted. For example, recommended TSH ranges are different for pregnant women, women with infertility, elderly patients or patients with cardiovascular disease, patients with thyroid cancer, patients with central hypothyroidism, etc.
The diagnosis of hypothyroidism itself may be incorrect. Studies have shown that up to 1 in 3 patients on thyroid hormone do not have true hypothyroidism, and their thyroid hormone can be successfully stopped.
You may have an additional undiagnosed concurrent disease, that has symptoms that can overlap with the symptoms of hypothyroidism.
Special populations:
Our approach on Hashimoto’s thyroiditis and hypothyroidism is different in women who are pregnant, and women with infertility, as both of these conditions can independently affect pregnancy and fertility. Depending on the clinical scenario, different approaches are used for consideration of levothyroxine initiation, or levothyroxine dose adjustment. It is also very important to note that pregnant women with hypothyroidism usually require immediate levothyroxine dose adjustment upon finding out that they are pregnant, as they have higher thyroid hormone requirements compared to their baseline thyroid hormone requirement prior to pregnancy. Pregnant women also need very frequent laboratory monitoring with tight control of thyroid levels starting immediately after finding out that they are pregnant, in order to avoid pregnancy complications associated with hypothyroidism, such as preeclampsia, preterm delivery, miscarriage, low birth weight, adverse effect on fetal neurocognitive development, etc. Thus, close observation and treatment by an endocrinologist is of utmost importance.
