Hypothyroidism is a condition in which the thyroid gland does not produce sufficient thyroid hormone. Thyroid hormone is an important one, as it has multiple effects on the functioning of almost every system in the body. Having low thyroid hormone levels causes many symptoms including fatigue, weight gain, hair and skin changes, and slowing of the heart rate.
There are several different causes of hypothyroidism. The most common is an autoimmune condition in which the body itself produces substances which attack the thyroid gland. This condition, called Hashimoto's disease, is almost always permanent, meaning that the thyroid gland does not recover and patients will end up needing treatment for the rest of their lives. Occasionally, some cases of Hashimoto's will improve over time and patients will not need to stay on treatment, but this is rare.
Other less common causes of hypothyroidism are sometimes transient. For example, certain medications, such as lithium, can cause hypothyroidism that may improve if the medications are stopped. Also, certain thyroid inflammations, such as the type that occurs after pregnancy, can be transient.
The bottom line is that you will need to see your primary care doctor
. If you are hypothyroid, you will need to take thyroid replacement therapy, at least for the time being.